Fabrication of low defectivity electrochromic devices

ABSTRACT

Prior electrochromic devices frequently suffer from high levels of defectivity. The defects may be manifest as pin holes or spots where the electrochromic transition is impaired. This is unacceptable for many applications such as electrochromic architectural glass. Improved electrochromic devices with low defectivity can be fabricated by depositing certain layered components of the electrochromic device in a single integrated deposition system. While these layers are being deposited and/or treated on a substrate, for example a glass window, the substrate never leaves a controlled ambient environment, for example a low pressure controlled atmosphere having very low levels of particles. These layers may be deposited using physical vapor deposition.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/610,716, filed on Sep. 11, 2012 and titled “FABRICATION OF LOWDEFECTIVITY ELECTROCHROMIC DEVICES,” which is a continuation of U.S.patent application Ser. No. 12/645,111, filed on Dec. 22, 2009 andtitled “FABRICATION OF LOW DEFECTIVITY ELECTROCHROMIC DEVICES,” whichclaims benefit of and priority to U.S. Provisional Patent ApplicationNo. 61/165,484, filed on Mar. 31, 2009 and titled “ALL-SOLID-STATEELECTROCHROMIC DEVICE;” all of which are hereby incorporated byreference in their entireties and for all purposes.

BACKGROUND

Electrochromism is a phenomenon in which a material exhibits areversible electrochemically-mediated change in an optical property whenplaced in a different electronic state, typically by being subjected toa voltage change. The optical property is typically one or more ofcolor, transmittance, absorbance, and reflectance. One well knownelectrochromic material, for example, is tungsten oxide (WO₃). Tungstenoxide is a cathodic electrochromic material in which a colorationtransition, transparent to blue, occurs by electrochemical reduction.

Electrochromic materials may be incorporated into, for example, windowsand mirrors. The color, transmittance, absorbance, and/or reflectance ofsuch windows and mirrors may be changed by inducing a change in theelectrochromic material. One well known application of electrochromicmaterials, for example, is the rear view mirror in some cars. In theseelectrochromic rear view mirrors, the reflectivity of the mirror changesat night so that the headlights of other vehicles are not distracting tothe driver.

While electrochromism was discovered in the 1960′s, electrochromicdevices still unfortunately suffer various problems and have not begunto realize their full commercial potential.

SUMMARY OF INVENTION

The inventors have observed that prior electrochromic devices frequentlysuffer from high levels of defectivity. The defects may be manifest aspin holes or spots where the electrochromic transition is impaired. Thisis unacceptable for many applications such as electrochromicarchitectural glass. In the case of an electrochromic window, forexample an architectural glass window, such defects may appear as brightspots or “constellations” when the window is electrochromicallydarkened. Persons occupying a room where such defective windows areinstalled will find that they are periodically distracted by the brightspots on the windows.

The inventors have discovered that improved electrochromic devices withlow defectivity can be fabricated by depositing certain layeredcomponents of the electrochromic device in a single integrateddeposition system. While these layers are being deposited and/or treatedon a substrate, for example a glass window, the substrate never leaves acontrolled ambient environment, for example a low pressure controlledatmosphere having very low levels of particles. In some embodiments, thelayers of interest are deposited using physical vapor deposition. Highlyreliable electrochromic devices may employ entirely solid inorganiccomponents.

In one embodiment, an electrochromic window is fabricated bysequentially depositing on a substrate (i) an electrochromic layer, (ii)an ion conducting layer, and (iii) a counter electrode layer. Theselayers form a stack in which the ion conducting layer separates theelectrochromic layer and the counter electrode layer. Each of thesequentially deposited layers is vapor deposited using a singleintegrated deposition system having a controlled ambient environment inwhich the pressure and gas composition are controlled independently ofan external environment outside of the integrated deposition system. Thesubstrate does not leave the integrated deposition system at any timeduring the sequential deposition of the electrochromic layer, the ionconducting layer, and the counter electrode layer.

In an embodiment of an integrated deposition system for fabricating anelectrochromic window, the system includes a plurality of depositionstations aligned in series and interconnected and operable to pass asubstrate from one station to the next without exposing the substrate toan external environment. The plurality of deposition stations include(i) a first deposition station containing a material source fordepositing an electrochromic layer; (ii) a second deposition stationcontaining a material source for depositing an ion conducting layer; and(iii) a third deposition station containing a material source fordepositing a counter electrode layer. The system further includes acontroller containing program instructions for passing the substratethrough the plurality of stations in a manner that sequentially depositson the substrate (i) an electrochromic layer, (ii) an ion conductinglayer, and (iii) a counter electrode layer to form a stack in which theion conducting layer separates the electrochromic layer and the counterelectrode layer.

These and other features and advantages of the invention will bedescribed in further detail below, with reference to the associateddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description can be more fully understood whenconsidered in conjunction with the drawings in which:

FIG. 1 is a schematic cross-section of an electrochromic device inaccordance with embodiments of the invention.

FIG. 2 is a schematic cross-section of an electrochromic device in ableached state in accordance with specific embodiments of the invention.

FIG. 3 is a schematic cross-section of an electrochromic device in acolored state in accordance with specific embodiments of the invention.

FIG. 4 is a schematic cross-section of an electrochromic device with aparticle in the ion conducting layer causing a localized defect in thedevice.

FIG. 5A is a schematic cross-section of an electrochromic device with aparticle on the conductive layer prior to depositing the remainder ofthe electrochromic stack.

FIG. 5B is a schematic cross-section of the electrochromic device ofFIG. 5A, where a “pop off” defect is formed during electrochromic stackformation.

FIG. 5C is a schematic cross-section of the electrochromic device ofFIG. 5B, showing an electrical short that is formed from the pop offdefect once the second conductive is deposited.

FIG. 6A depicts a cross-sectional representation of an electrochromicwindow device in accord with the multistep process description providedin relation to FIG. 7A.

FIG. 6B depicts a top view of an electrochromic device showing locationof trenches cut into the device.

FIG. 7A depicts a process flow describing a method of fabricating anelectrochromic window.

FIGS. 7B-7D depict methods of fabricating an electrochromic stack whichis part of an electrochromic device of the invention.

FIG. 7E depicts a process flow for a conditioning process used tofabricate an electrochromic device of the invention.

FIG. 8A, depicts an integrated deposition system of the invention.

FIG. 8B depicts an integrated deposition system in a perspective view.

FIG. 8C depicts a modular integrated deposition system.

FIG. 8D depicts an integrated deposition system with two lithiumdeposition stations.

FIG. 8E depicts an integrated deposition system with one lithiumdeposition station.

DETAILED DESCRIPTION

Electrochromic Devices

A schematic cross-section of an electrochromic device 100 in accordancewith some embodiments is shown in FIG. 1. The electrochromic deviceincludes a substrate 102, a conductive layer (CL) 104, an electrochromiclayer (EC) 106, an ion conducting layer (IC) 108, a counter electrodelayer (CE) 110, and a conductive layer (CL) 114. Elements 104, 106, 108,110, and 114 are collectively referred to as an electrochromic stack120. A voltage source 116 operable to apply an electric potential acrossthe electrochromic stack 120 effects the transition of theelectrochromic device from, e.g., a bleached state to a colored state.In other embodiments, the order of layers is reversed with respect tothe substrate. That is, the layers are in the following order:substrate, conductive layer, counter electrode layer, ion conductinglayer, electrochromic material layer, conductive layer.

It should be understood that the reference to a transition between ableached state and colored state is non-limiting and suggests only oneexample, among many, of an electrochromic transition that may beimplemented. Unless otherwise specified herein, whenever reference ismade to a bleached-colored transition, the corresponding device orprocess encompasses other optical state transitions suchnon-reflective-reflective, transparent-opaque, etc. Further the term“bleached” refers to an optically neutral state, e.g., uncolored,transparent or translucent. Still further, unless specified otherwiseherein, the “color” of an electrochromic transition is not limited toany particular wavelength or range of wavelengths. As understood bythose of skill in the art, the choice of appropriate electrochromic andcounter electrode materials governs the relevant optical transition.

In certain embodiments, the electrochromic device reversibly cyclesbetween a bleached state and a colored state. In the bleached state, apotential is applied to the electrochromic stack 120 such that availableions in the stack that can cause the electrochromic material 106 to bein the colored state reside primarily in the counter electrode 110. Whenthe potential on the electrochromic stack is reversed, the ions aretransported across the ion conducting layer 108 to the electrochromicmaterial 106 and cause the material to enter the colored state. A moredetailed description of the transition from bleached to colored state,and from colored to bleached state, is included below in the descriptionof FIGS. 2 and 3, but first the individual layers of stack 120 will bedescribed in more detail in relation to FIG. 1.

In certain embodiments, all of the materials making up electrochromicstack 120 are inorganic, solid (i.e., in the solid state), or bothinorganic and solid. Because organic materials tend to degrade overtime, inorganic materials offer the advantage of a reliableelectrochromic stack that can function for extended periods of time.Materials in the solid state also offer the advantage of not havingcontainment and leakage issues, as materials in the liquid state oftendo. Each of the layers in the electrochromic device is discussed indetail, below. It should be understood that any one or more of thelayers in the stack may contain some amount of organic material, but inmany implementations one or more of the layers contains little or noorganic matter. The same can be said for liquids that may be present inone or more layers in small amounts. It should also be understood thatsolid state material may be deposited or otherwise formed by processesemploying liquid components such as certain processes employing sol-gelsor chemical vapor deposition.

Referring again to FIG. 1, voltage source 116 is typically a low voltageelectrical source and may be configured to operate in conjunction withradiant and other environmental sensors. Voltage source 116 may also beconfigured to interface with an energy management system, such as acomputer system that controls the electrochromic device according tofactors such as the time of year, time of day, and measuredenvironmental conditions. Such an energy management system, inconjunction with large area electrochromic devices (i.e., anelectrochromic window), can dramatically lower the energy consumption ofa building.

Any material having suitable optical, electrical, thermal, andmechanical properties may be used as substrate 102. Such substratesinclude, for example, glass, plastic, and mirror materials. Suitableplastic substrates include, for example acrylic, polystyrene,polycarbonate, allyl diglycol carbonate, SAN (styrene acrylonitrilecopolymer), poly(4-methyl-1-pentene), polyester, polyamide, etc. If aplastic substrate is used, it is preferably barrier protected andabrasion protected using a hard coat of, for example, a diamond-likeprotection coating, a silica/silicone anti-abrasion coating, or thelike, such as is well known in the plastic glazing art. Suitable glassesinclude either clear or tinted soda lime glass, including soda limefloat glass. The glass may be tempered or untempered. In someembodiments of electrochromic device 100 with glass, e.g. soda limeglass, used as substrate 102, there is a sodium diffusion barrier layer(not shown) between substrate 102 and conductive layer 104 to preventthe diffusion of sodium ions from the glass into conductive layer 104.

In some embodiments, the optical transmittance (i.e., the ratio oftransmitted radiation or spectrum to incident radiation or spectrum) ofsubstrate 102 is about 40 to 95%, e.g., about 90-92%. The substrate maybe of any thickness, as long as it has suitable mechanical properties tosupport the electrochromic stack 120. While the substrate 102 may be ofany size, in some embodiments, it is about 0.01 mm to 10 mm thick,preferably about 3 mm to 9 mm thick.

In some embodiments of the invention, the substrate is architecturalglass. Architectural glass is glass that is used as a building material.Architectural glass is typically used in commercial buildings, but mayalso be used in residential buildings, and typically, though notnecessarily, separates an indoor environment from an outdoorenvironment. In certain embodiments, architectural glass is at least 20inches by 20 inches, and can be much larger, e.g., as large as about 72inches by 120 inches. Architectural glass is typically at least about 2mm thick. Architectural glass that is less than about 3.2 mm thickcannot be tempered. In some embodiments of the invention witharchitectural glass as the substrate, the substrate may still betempered even after the electrochromic stack has been fabricated on thesubstrate. In some embodiments with architectural glass as thesubstrate, the substrate is a soda lime glass from a tin float line. Thepercent transmission over the visible spectrum of an architectural glasssubstrate (i.e., the integrated transmission across the visiblespectrum) is generally greater than 80% for neutral substrates, but itcould be lower for colored substrates. Preferably, the percenttransmission of the substrate over the visible spectrum is at leastabout 90% (e.g., about 90-92%). The visible spectrum is the spectrumthat a typical human eye will respond to, generally about 380 nm(purple) to about 780 nm (red). In some cases, the glass has a surfaceroughness of between about 10 and 30 nm.

On top of substrate 102 is conductive layer 104. In certain embodiments,one or both of the conductive layers 104 and 114 is inorganic and/orsolid. Conductive layers 104 and 114 may be made from a number ofdifferent materials, including conductive oxides, thin metalliccoatings, conductive metal nitrides, and composite conductors.

Typically, conductive layers 104 and 114 are transparent at least in therange of wavelengths where electrochromism is exhibited by theelectrochromic layer. Transparent conductive oxides include metal oxidesand metal oxides doped with one or more metals. Examples of such metaloxides and doped metal oxides include indium oxide, indium tin oxide,doped indium oxide, tin oxide, doped tin oxide, zinc oxide, aluminumzinc oxide, doped zinc oxide, ruthenium oxide, doped ruthenium oxide andthe like. Since oxides are often used for these layers, they aresometimes referred to as “transparent conductive oxide” (TCO) layers.Thin metallic coatings that are substantially transparent may also beused. Examples of metals used for such thin metallic coatings includetransition metals including gold, platinum, silver, aluminum, nickelalloy, and the like. Thin metallic coatings based on silver, well knownin the glazing industry, are also used. Examples of conductive nitridesinclude titanium nitrides, tantalum nitrides, titanium oxynitrides, andtantalum oxynitrides. The conductive layers 104 and 114 may also becomposite conductors. Such composite conductors may be fabricated byplacing highly conductive ceramic and metal wires or conductive layerpatterns on one of the faces of the substrate and then over-coating withtransparent conductive materials such as doped tin oxides or indium tinoxide. Ideally, such wires should be thin enough as to be invisible tothe naked eye (e.g., about 100 μm or thinner).

In some embodiments, commercially available substrates such as glasssubstrates contain a transparent conductive layer coating. Such productsmay be used for both substrate 102 and conductive layer 104. Examples ofsuch glasses include conductive layer coated glasses sold under thetrademark TEC Glass™ by Pilkington, of Toledo, Ohio and SUNGATE™ 300 andSUNGATE™ 500 by PPG Industries of Pittsburgh, Pa. TEC Glass™ is a glasscoated with a fluorinated tin oxide conductive layer.

In some embodiments of the invention, the same conductive layer is usedfor both conductive layers (i.e., conductive layers 104 and 114). Insome embodiments, different conductive materials are used for eachconductive layer 104 and 114. For example, in some embodiments, TECGlass™ is used for substrate 102 (float glass) and conductive layer 104(fluorinated tin oxide) and indium tin oxide is used for conductivelayer 114. As noted above, in some embodiments employing TEC Glass™there is a sodium diffusion barrier between the glass substrate 102 andTEC conductive layer 104.

In some implementations, the composition of a conductive layer, asprovided for fabrication, should be chosen or tailored based on thecomposition of an adjacent layer (e.g., electrochromic layer 106 orcounter electrode layer 110) in contact with the conductive layer. Formetal oxide conductive layers, for example, conductivity is a functionof the number of oxygen vacancies in the conductive layer material, andthe number of oxygen vacancies in the metal oxide is impacted by thecomposition of the adjacent layer. Selection criteria for a conductivelayer may also include the material's electrochemical stability andability to avoid oxidation or more commonly reduction by a mobile ionspecies.

The function of the conductive layers is to spread an electric potentialprovided by voltage source 116 over surfaces of the electrochromic stack120 to interior regions of the stack, with very little ohmic potentialdrop. The electric potential is transferred to the conductive layersthough electrical connections to the conductive layers. In someembodiments, bus bars, one in contact with conductive layer 104 and onein contact with conductive layer 114, provide the electric connectionbetween the voltage source 116 and the conductive layers 104 and 114.The conductive layers 104 and 114 may also be connected to the voltagesource 116 with other conventional means.

In some embodiments, the thickness of conductive layers 104 and 114 isbetween about 5 nm and about 10,000 nm. In some embodiments, thethickness of conductive layers 104 and 114 are between about 10 nm andabout 1,000 nm. In other embodiments, the thickness of conductive layers104 and 114 are between about 10 nm and about 500 nm. In someembodiments where TEC Glass™ is used for substrate 102 and conductivelayer 104, the conductive layer is about 400 nm thick. In someembodiments where indium tin oxide is used for conductive layer 114, theconductive layer is about 100 nm to 400 nm thick (280 nm in oneembodiment). More generally, thicker layers of the conductive materialmay be employed so long as they provide the necessary electricalproperties (e.g., conductivity) and optical properties (e.g.,transmittance). Generally, the conductive layers 104 and 114 are as thinas possible to increase transparency and to reduce cost. In someembodiment, conductive layers are substantially crystalline. In someembodiment, conductive layers are crystalline with a high fraction oflarge equiaxed grains

The thickness of the each conductive layer 104 and 114 is alsosubstantially uniform. Smooth layers (i.e., low roughness, Ra) of theconductive layer 104 are desirable so that other layers of theelectrochromic stack 120 are more compliant. In one embodiment, asubstantially uniform conductive layer varies by no more than about +10%in each of the aforementioned thickness ranges. In another embodiment, asubstantially uniform conductive layer varies by no more than about ±5%in each of the aforementioned thickness ranges. In another embodiment, asubstantially uniform conductive layer varies by no more than about ±2%in each of the aforementioned thickness ranges.

The sheet resistance (R_(s)) of the conductive layers is also importantbecause of the relatively large area spanned by the layers. In someembodiments, the sheet resistance of conductive layers 104 and 114 isabout 5 to 30 Ohms per square. In some embodiments, the sheet resistanceof conductive layers 104 and 114 is about 15 Ohms per square. Ingeneral, it is desirable that the sheet resistance of each of the twoconductive layers be about the same. In one embodiment, the two layerseach have a sheet resistance of about 10-15 Ohms per square.

Overlaying conductive layer 104 is electrochromic layer 106. Inembodiments of the invention, electrochromic layer 106 is inorganicand/or solid, in typical embodiments inorganic and solid. Theelectrochromic layer may contain any one or more of a number ofdifferent electrochromic materials, including metal oxides. Such metaloxides include tungsten oxide (WO₃), molybdenum oxide (MoO₃), niobiumoxide (Nb₂O₅), titanium oxide (TiO₂), copper oxide (CuO), iridium oxide(Ir₂O₃), chromium oxide (Cr₂O₃), manganese oxide (Mn₂O₃), vanadium oxide(V₂O₅), nickel oxide (Ni₂O₃), cobalt oxide (Co₂O₃) and the like. In someembodiments, the metal oxide is doped with one or more dopants such aslithium, sodium, potassium, molybdenum, vanadium, titanium, and/or othersuitable metals or compounds containing metals. Mixed oxides (e.g., W-Mooxide, W-V oxide) are also used in certain embodiments. Anelectrochromic layer 106 comprising a metal oxide is capable ofreceiving ions transferred from counter electrode layer 110.

In some embodiments, tungsten oxide or doped tungsten oxide is used forelectrochromic layer 106. In one embodiment of the invention, theelectrochromic layer is made substantially of WO_(x), where “x” refersto an atomic ratio of oxygen to tungsten in the electrochromic layer,and x is between about 2.7 and 3.5. It has been suggested that onlysub-stoichiometric tungsten oxide exhibits electrochromism; i.e.,stoichiometric tungsten oxide, WO₃, does not exhibit electrochromism. Ina more specific embodiment, WO_(x), where x is less than 3.0 and atleast about 2.7 is used for the electrochromic layer. In anotherembodiment, the electrochromic layer is WOx, where x is between about2.7 and about 2.9. Techniques such as Rutherford BackscatteringSpectroscopy (RBS) can identify the total number of oxygen atoms whichinclude those bonded to tungsten and those not bonded to tungsten. Insome instances, tungsten oxide layers where x is 3 or greater exhibitelectrochromism, presumably due to unbound excess oxygen along withsub-stoichiometric tungsten oxide. In another embodiment, the tungstenoxide layer has stoichiometric or greater oxygen, where x is 3.0 toabout 3.5.

In certain embodiments, the tungsten oxide is crystalline,nanocrystalline, or amorphous. In some embodiments, the tungsten oxideis substantially nanocrystalline, with grain sizes, on average, fromabout 5 nm to 50 nm (or from about 5 nm to 20 nm), as characterized bytransmission electron microscopy (TEM). The tungsten oxide morphologymay also be characterized as nanocrystalline using x-ray diffraction(XRD); XRD. For example, nanocrystalline electrochromic tungsten oxidemay be characterized by the following XRD features: a crystal size ofabout 10 to 100 nm (e.g., about 55nm. Further, nanocrystalline tungstenoxide may exhibit limited long range order, e.g., on the order ofseveral (about 5 to 20) tungsten oxide unit cells.

The thickness of the electrochromic layer 106 depends on theelectrochromic material selected for the electrochromic layer. In someembodiments, the electrochromic layer 106 is about 50 nm to 2,000 nm, orabout 200 nm to 700 nm. In some embodiments, the electrochromic layer isabout 300 nm to about 500 nm. The thickness of the electrochromic layer106 is also substantially uniform. In one embodiment, a substantiallyuniform electrochromic layer varies only about ±10% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform electrochromic layer varies only about ±5% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform electrochromic layer varies only about ±3% in each of theaforementioned thickness ranges.

Generally, in electrochromic materials, the colorization (or change inany optical property—e.g., absorbance, reflectance, and transmittance)of the electrochromic material is caused by reversible ion insertioninto the material (e.g., intercalation) and a corresponding injection ofa charge balancing electron. Typically some fraction of the ionresponsible for the optical transition is irreversibly bound up in theelectrochromic material. As explained below some or all of theirreversibly bound ions are used to compensate “blind charge” in thematerial. In most electrochromic materials, suitable ions includelithium ions (Li⁺) and hydrogen ions (H⁺) (i.e., protons). In somecases, however, other ions will be suitable. These include, for example,deuterium ions (D⁺), sodium ions (Na⁺), potassium ions (K⁺), calciumions (Ca⁺⁺), barium ions (Ba⁺⁺), strontium ions (Sr⁺⁺), and magnesiumions (Mg⁺⁺). In various embodiments described herein, lithium ions areused to produce the electrochromic phenomena. Intercalation of lithiumions into tungsten oxide (WO_(3-y) (0<y≦˜0.3)) causes the tungsten oxideto change from transparent (bleached state) to blue (colored state).

Referring again to FIG. 1, in electrochromic stack 120, ion conductinglayer 108 overlays electrochromic layer 106. On top of ion conductinglayer 108 is counter electrode layer 110. In some embodiments, counterelectrode layer 110 is inorganic and/or solid. The counter electrodelayer may comprise one or more of a number of different materials thatare capable of serving as reservoirs of ions when the electrochromicdevice is in the bleached state. During an electrochromic transitioninitiated by, e.g., application of an appropriate electric potential,the counter electrode layer transfers some or all of the ions it holdsto the electrochromic layer, changing the electrochromic layer to thecolored state. Concurrently, in the case of NiWO, the counter electrodelayer colors with the loss of ions.

In some embodiments, suitable materials for the counter electrodecomplementary to WO₃ include nickel oxide (NiO), nickel tungsten oxide(NiWO), nickel vanadium oxide, nickel chromium oxide, nickel aluminumoxide, nickel manganese oxide, nickel magnesium oxide, chromium oxide(Cr₂O₃), manganese oxide (MnO₂), Prussian blue. Optically passivecounter electrodes comprise cerium titanium oxide (CeO₂—TiO₂), ceriumzirconium oxide (CeO₂—ZrO₂), nickel oxide (NiO), nickel-tungsten oxide(NiWO), vanadium oxide (V₂O₅), and mixtures of oxides (e.g., a mixtureof Ni₂O₃ and W0₃). Doped formulations of these oxides may also be used,with dopants including, e.g., tantalum and tungsten. Because counterelectrode layer 110 contains the ions used to produce the electrochromicphenomenon in the electrochromic material when the electrochromicmaterial is in the bleached state, the counter electrode preferably hashigh transmittance and a neutral color when it holds significantquantities of these ions.

In some embodiments, nickel-tungsten oxide (NiWO) is used in the counterelectrode layer. In certain embodiments, the amount of nickel present inthe nickel-tungsten oxide can be up to about 90% by weight of thenickel-tungsten oxide. In a specific embodiment, the mass ratio ofnickel to tungsten in the nickel-tungsten oxide is between about 4:6 and6:4 (e.g., about 1:1). In one embodiment, the NiWO is between about 15%(atomic) Ni and about 60% Ni; between about 10% W and about 40% W; andbetween about 30% 0 and about 75% 0. In another embodiment, the NiWO isbetween about 30% (atomic) Ni and about 45% Ni; between about 10% W andabout 25% W; and between about 35% 0 and about 50% 0. In one embodiment,the NiWO is about 42% (atomic) Ni, about 14% W, and about 44% 0.

When charge is removed from a counter electrode 110 made of nickeltungsten oxide (i.e., ions are transported from the counter electrode110 to the electrochromic layer 106), the counter electrode layer willturn from a transparent state to a brown colored state.

The counter electrode morphology may be crystalline, nanocrystalline, oramorphous. In some embodiments, where the counter electrode layer isnickel-tungsten oxide, the counter electrode material is amorphous orsubstantially amorphous. Substantially amorphous nickel-tungsten oxidecounter electrodes have been found to perform better, under someconditions, in comparison to their crystalline counterparts. Theamorphous state of the nickel-tungsten oxide may be obtained though theuse of certain processing conditions, described below. While not wishingto be bound to any theory or mechanism, it is believed that amorphousnickel-tungsten oxide is produced by relatively higher energy atoms inthe sputtering process. Higher energy atoms are obtained, for example,in a sputtering process with higher target powers, lower chamberpressures (i.e., higher vacuum), and smaller source to substratedistances. Under the described process conditions, higher density films,with better stability under UV/heat exposure are produced.

In some embodiments, the thickness of the counter electrode is about 50nm about 650 nm. In some embodiments, the thickness of the counterelectrode is about 100 nm to about 400 nm, preferably in the range ofabout 200 nm to 300 nm. The thickness of the counter electrode layer 110is also substantially uniform. In one embodiment, a substantiallyuniform counter electrode layer varies only about ±10% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform counter electrode layer varies only about ±5% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform counter electrode layer varies only about ±3% in each of theaforementioned thickness ranges.

The amount of ions held in the counter electrode layer during thebleached state (and correspondingly in the electrochromic layer duringthe colored state) and available to drive the electrochromic transitiondepends on the composition of the layers as well as the thickness of thelayers and the fabrication method. Both the electrochromic layer and thecounter electrode layer are capable of supporting available charge (inthe form of lithium ions and electrons) in the neighborhood of severaltens of millicoulombs per square centimeter of layer surface area. Thecharge capacity of an electrochromic film is the amount of charge thatcan be loaded and unloaded reversibly per unit area and unit thicknessof the film by applying an external voltage or potential. In oneembodiment, the WO₃ layer has a charge capacity of between about 30 andabout 150 mC/cm²/micron. In another embodiment, the WO₃ layer has acharge capacity of between about 50 and about 100 mC/cm²/micron. In oneembodiment, the NiWO layer has a charge capacity of between about 75 andabout 200 mC/cm²/micron. In another embodiment, the NiWO layer has acharge capacity of between about 100 and about 150 mC/cm²/micron.

In between electrochromic layer 106 and counter electrode layer 110,there is an ion conducting layer 108. Ion conducting layer 108 serves asa medium through which ions are transported (in the manner of anelectrolyte) when the electrochromic device transforms between thebleached state and the colored state. Preferably, ion conducting layer108 is highly conductive to the relevant ions for the electrochromic andthe counter electrode layers, but has sufficiently low electronconductivity that negligible electron transfer takes place during normaloperation. A thin ion conducting layer with high ionic conductivitypermits fast ion conduction and hence fast switching for highperformance electrochromic devices. In certain embodiments, the ionconducting layer 108 is inorganic and/or solid. When fabricated from amaterial and in a manner that produces relatively few defects, the ionconductor layer can be made very thin to produce a high performancedevice. In various implementations, the ion conductor material has anionic conductivity of between about 10⁸ Siemens/cm or ohm⁻¹ cm⁻¹ andabout 10⁹ Siemens/cm or ohm⁻¹ cm⁻¹ and an electronic resistance of about10¹¹ ohms-cm.

Examples of suitable ion conducting layers include silicates, siliconoxides, tungsten oxides, tantalum oxides, niobium oxides, and borates.The silicon oxides include silicon-aluminum-oxide. These materials maybe doped with different dopants, including lithium. Lithium dopedsilicon oxides include lithium silicon-aluminum-oxide.

In some embodiments, the ion conducting layer comprises a silicate-basedstructure. In other embodiments, suitable ion conductors particularlyadapted for lithium ion transport include, but are not limited to,lithium silicate, lithium aluminum silicate, lithium aluminum borate,lithium aluminum fluoride, lithium borate, lithium nitride, lithiumzirconium silicate, lithium niobate, lithium borosilicate, lithiumphosphosilicate, and other such lithium-based ceramic materials,silicas, or silicon oxides, including lithium silicon-oxide. Anymaterial, however, may be used for the ion conducting layer 108 providedit can be fabricated with low defectivity and it allows for the passageof ions between the counter electrode layer 110 to the electrochromiclayer 106 while substantially preventing the passage of electrons.

In certain embodiments, the ion conducting layer is crystalline,nanocrystalline, or amorphous. Typically, the ion conducting layer isamorphous. In another embodiment, the ion conducting layer isnanocrystalline. In yet another embodiment, the ion conducting layer iscrystalline.

In some embodiments, a silicon-aluminum-oxide (SiAlO) is used for theion conducting layer 108. In a specific embodiment, a silicon/aluminumtarget used to fabricate the ion conductor layer via sputtering containsbetween about 6 and about 20 atomic percent aluminum. This defines theratio of silicon to aluminum in the ion conducting layer. In someembodiments, the silicon-aluminum-oxide ion conducting layer 108 isamorphous.

The thickness of the ion conducting layer 108 may vary depending on thematerial. In some embodiments, the ion conducting layer 108 is about 5nm to 100 nm thick, preferably about 10 nm to 60 nm thick. In someembodiments, the ion conducting layer is about 15 nm to 40 nm thick orabout 25 nm to 30 nm thick. The thickness of the ion conducting layer isalso substantially uniform. In one embodiment, a substantially uniformion conducting layer varies by not more than about ±10% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform ion conducting layer varies by not more than about ±5% in eachof the aforementioned thickness ranges. In another embodiment, asubstantially uniform ion conducting layer varies by not more than about±3% in each of the aforementioned thickness ranges.

Ions transported across the ion conducting layer between theelectrochromic layer and the counter electrode layer serve to effect acolor change in the electrochromic layer (i.e., change theelectrochromic device from the bleached state to the colored state).

Depending on the choice of materials for the electrochromic devicestack, such ions include lithium ions (Li⁺) and hydrogen ions (Cl⁺)(i.e., protons). As mentioned above, other ions may be employed incertain embodiments. These include deuterium ions (D⁺), sodium ions(Na⁺), potassium ions (K⁺), calcium ions (Ca⁺⁺), barium ions (Ba⁺⁺),strontium ions (Sr⁺⁺), and magnesium ions (Mg⁺⁺).

As noted, the ion conducting layer 108 should have very few defects.Among other problems, defects in the ion conducting layer may result inshort circuits between the electrochromic layer and the counterelectrode layer (described in more detail below in relation to FIG. 4).A short circuit occurs when electrical communication is establishedbetween oppositely charged conductive layers, e.g. a conductive particlemakes contact with each of two conductive and electrically chargedlayers (as opposed to a “pin hole” which is a defect which does notcreate a short circuit between oppositely charged conductive layers).When a short circuit occurs, electrons rather than ions migrate betweenthe electrochromic layer and the counter electrode, typically resultingin bright spots (i.e., spots where the window does not switch butinstead, maintains the open circuit coloration which is often muchlighter than the colored state) at the location of the short when theelectrochromic device is otherwise in the colored state. The ionconducting layer is preferably as thin as possible, without any shortsbetween the electrochromic layer and the counter electrode layer. Asindicated, low defectivity in the ion conducting layer 108 (or elsewherein the electrochromic device) allows for a thinner ion conducting layer108. Ion transport between the electrochromic layer and the counterelectrode layer with electrochemical cycling is faster when using a thinion conducting layer. To generalize, the defectivity criteria specifiedherein may apply to any specific layer (ion conducting layer orotherwise) in the stack or to the stack as a whole or to any portionthereof. Defectivity criteria will be further discussed below.

The electrochromic device 100 may include one or more additional layers(not shown) such as one or more passive layers. Passive layers used toimprove certain optical properties may be included in electrochromicdevice 100. Passive layers for providing moisture or scratch resistancemay also be included in the electrochromic device 100. For example, theconductive layers may be treated with anti-reflective or protectiveoxide or nitride layers. Other passive layers may serve to hermeticallyseal the electrochromic device 100.

FIG. 2 is a schematic cross-section of an electrochromic device in ableached state (or transitioning to a bleached state). In accordancewith specific embodiments, the electrochromic device 200 includes atungsten oxide electrochromic layer (EC) 206 and a nickel-tungsten oxidecounter electrode layer (CE) 210. In some cases, the tungsten oxideelectrochromic layer 206 has a nanocrystalline, or substantiallynanocrystalline, morphology. In some embodiments, the nickel-tungstenoxide counter electrode layer 210 has an amorphous, or substantiallyamorphous, morphology. In some embodiments, the weight percent ratio oftungsten to nickel in the nickel-tungsten oxide is about 0.40-0.60

The electrochromic device 200 also includes substrate 202, conductivelayer (CL) 204, ion conducting layer (IC) 208, and conductive layer (CL)214. In some embodiments, the substrate 202 and conductive layer 204together comprise a TEC-Glass™. As indicated, the electrochromic devicesdescribed herein, such as those of FIG. 2, often find beneficialapplication in architectural glass. Thus, in some embodiments, thesubstrate 202 is of the dimensions such that it may be classified asarchitectural glass. In some embodiments, the conductive layer 214 isindium tin oxide (ITO). In some embodiments, the ion conducting layer208 is a silicon-aluminum-oxide.

The voltage source 216 is configured to apply a potential toelectrochromic stack 220 through suitable connections (e.g., bus bars)to conductive layers 204 and 214. In some embodiments, the voltagesource is configured to apply a potential of about 2 volts in order todrive a transition of the device from one optical state to another. Thepolarity of the potential as shown in FIG. 2 is such that the ions(lithium ions in this example) primarily reside in the nickel-tungstenoxide counter electrode layer 210.

In embodiments employing tungsten oxide as the electrochromic layer andnickel-tungsten oxide as the counter electrode layer, the ratio of theelectrochromic layer thickness to the counter electrode layer thicknessmay be about 1.7:1 to 2.3:1 (e.g., about 2:1). In some embodiments, theelectrochromic tungsten oxide layer is about 200 nm to 700 nm thick. Infurther embodiments, the electrochromic tungsten oxide layer is about400 nm to 500 nm thick. In some embodiments, the nickel-tungsten oxidecounter electrode layer is about 100 nm to 350 nm thick. In furtherembodiments, and the nickel-tungsten oxide counter electrode layer isabout 200 nm to 250 nm thick. In yet further embodiments, thenickel-tungsten oxide counter electrode layer is about 240 nm thick.Also, in some embodiments, the silicon-aluminum-oxide ion conductinglayer 208 is about 10 nm to 100 nm thick. In further embodiments, thesilicon-aluminum-oxide ion conducting layer is about 20 nm to 50 nmthick.

As indicated above, electrochromic materials may contain blind charge.The blind charge in an electrochromic material is the charge (e.g.,negative charge in the cases of tungsten oxide electrochromic material)that exists in the material as fabricated, absent compensation byoppositely charged ions or other charge carriers. With tungsten oxide,for example, the magnitude of the blind charge depends upon the excessoxygen concentration during sputtering of the tungsten oxide.Functionally, blind charge must be compensated before the ions employedto transform the electrochromic material can effectively change anoptical property of the electrochromic material. Without priorcompensation of the blind charge, ions supplied to an electrochromicmaterial will irreversibly incorporate in the material and have noeffect on the optical state of the material. Thus, an electrochromicdevice is typically provided with ions, such as lithium ions or protons,in an amount sufficient both to compensate the blind charge and toprovide a supply of ions for reversibly switching the electrochromicmaterial between two optical states. In many known electrochromicdevices, charge is lost during the first electrochemical cycle incompensating blind charge.

In some embodiments, lithium is present in the electrochromic stack 220in an amount sufficient to compensate the blind charge in theelectrochromic layer 206 and then an additional amount of about 1.5 to2.5 times the amount used to compensate the blind charge (by mass) inthe stack (initially in the counter electrode layer 210 for example).That is, there is about 1.5 to 2.5 times the amount of lithium needed tocompensate the blind charge that is provided for reversible cyclingbetween the electrochromic layer 206 and the counter electrode layer 210in the electrochromic stack 220. In some embodiments, there are enoughlithium in the electrochromic stack 220 to compensate the blind chargein the electrochromic layer 206 and then about two times this amount (bymass) in the counter electrode layer 210 or elsewhere in the stack.

FIG. 3 is a schematic cross-section of electrochromic device 200 shownin FIG. 2 but in a colored state (or transitioning to a colored state).In FIG. 3, the polarity of voltage source 216 is reversed, so that theelectrochromic layer is made more negative to accept additional lithiumions, and thereby transition to the colored state. As shown, lithiumions are transported across the ion conducting layer 208 to the tungstenoxide electrochromic layer 206. The tungsten oxide electrochromic layer206 is shown in the colored state. The nickel-tungsten oxide counterelectrode 210 is also shown in the colored state. As explained,nickel-tungsten oxide becomes progressively more opaque as it gives up(deintercalates) lithium ions. In this example, there is a synergisticeffect where the transition to colored states for both layers 206 and210 are additive toward reducing the amount of light transmitted throughthe stack and substrate.

In certain embodiments, electrochromic devices of the types describedabove are very reliable, often substantially more so than counterpartdevices of the prior art. Reliability may be characterized by variousmetrics. Some of these are described in ASTM E2141-06 (Standard TestMethods for Assessing the Durability of Absorptive ElectrochromicCoatings on Sealed Insulating Glass Units). In some specific cases, thedevices are able to cycle between two distinct optical states (e.g.,between bleached and colored) over 50,000 times while maintaining aratio of the bleached T_(vis) to colored T_(vis) (also know as PTR orphotopic transmission ratio) of >4. The longevity of theseelectrochromic devices makes them suitable for use in applications wherethe electrochromic devices are expected to be in place for tens ofyears. Furthermore, the electrochromic devices in embodiments of theinvention are able to cycle between bleached and unbleached stateswithout losing transmissivity in the bleached state and withoutdegradation of the color or other property in the unbleached state. Insome cases, the high reliability of an electrochromic device inaccordance with embodiments herein described is due in part to a designin which the thickness of the electrochromic layer and/or the thicknessof the counter electrode layer in a stack do not substantially changeduring electrochemical cycling of the electrochromic device from theiras deposited, post lithiation thickness (e.g., by no more than about4%).

As indicated above, many electrochromic devices as described herein havea reduced number of defects; i.e., considerably fewer than are presentin comparable prior devices. As used herein, the term “defect” refers toa defective point or region of an electrochromic device. Defects may becaused by electrical shorts or by pinholes. Further, defects may becharacterized as visible or non-visible. In general, a defect in anelectrochromic device does not change optical state (e.g., color) inresponse to an applied potential that is sufficient to causenon-defective regions of the electrochromic device to color or otherwisechange optical state. Often a defect will be manifest as visuallydiscernable anomalies in the electrochromic window or other device. Suchdefects are referred to herein as “visible” defects. Other defects areso small that they are not visually noticeable to the observer in normaluse (e.g., such defects do not produce a noticeable light point when thedevice is in the colored state during daytime). A short is a localizedelectronically conductive pathway spanning the ion conducting layer(e.g., an electronically conductive pathway between the two TCO layers).A pinhole is a region where one or more layers of the electrochromicdevice are missing or damaged so that electrochromism is not exhibited.Pinholes are not electrical shorts. Three types of defects are ofprimary concern: (1) visible pinholes, (2) visible shorts, and (3)non-visible shorts. Typically, though not necessarily, a visible shortwill have defect dimension of at least about 3 micrometers resulting ina region, e.g. of about 1 cm in diameter, where the electrochromiceffect is perceptibly diminished—these regions can be reducedsignificantly by isolating the defect causing the visible short so thatto the naked eye the visible short will resemble only a visible pinhole.A visible pinhole will have a defect dimension of at least about 100micrometers.

In some cases, an electrical short is created by a conductive particlelodging in the ion conducting layer, thereby causing an electronic pathbetween the counter electrode layer and the electrochromic layer or theTCO associated with either one of them. In some other cases, a defect iscaused by a particle on the substrate (on which the electrochromic stackis fabricated) and such particle causes layer delamination (sometimescalled “pop-off”) or the layers not to adhere to the substrate. Bothtypes of defects are illustrated below in FIGS. 4 and 5A-5C. Adelamination or pop-off defect can lead to a short if it occurs before aTCO or associated EC or CE is deposited. In such cases, the subsequentlydeposited TCO or EC/CE layer will directly contact an underlying TCO orCE/EC layer providing direct electronic conductive pathway. A fewexamples of defect sources are presented in the table below. The tablebelow is intended to provide examples of mechanisms that lead to thedifferent types of visible and non-visible defects. Additional factorsexist which may influence how the EC window responds to a defect withinthe stack.

Particle Location Worst Case Failure Effect On float Pops off leavingpinhole Pinhole On TEC Pops off allowing ITO- Visible short TEC shortVoltage drop On EC Leakage across IC Visible short Voltage drop On ICPops off leaving pinhole Pinhole On CE Pops off leaving pinhole Pinhole

An electrical short, even a non-visible one, can cause leakage currentacross the ion conducting layer and result in a potential drop in thevicinity of the short. If the potential drop is of sufficient magnitudeit will prevent the electrochromic device from undergoing anelectrochromic transition in the vicinity of the short. In the case of avisible short the defect will appear as a light central region (when thedevice is in the colored state) with a diffuse boundary such that thedevice gradually darkens with distance from the center of the short. Ifthere are a significant number of electrical shorts (visible ornon-visible) concentrated in an area of an electrochromic device, theymay collectively impact a broad region of the device whereby the devicecannot switch in such region. This is because the potential differencebetween the EC and CE layers in such regions cannot attain a thresholdlevel required to drive ions across the ion conductive layer. In certainimplementations described herein, the shorts (both visible andnon-visible) are sufficiently well controlled that the leakage currentdoes not have this effect anywhere on the device. It should beunderstood that leakage current may result from sources other thanshort-type defects. Such other sources include broad-based leakageacross the ion conducting layer and edge defects such as roll offdefects as described elsewhere herein and scribe line defects. Theemphasis here is on leakage caused only by points of electrical shortingacross the ion conducting layer in the interior regions of theelectrochromic device.

FIG. 4 is a schematic cross-section of an electrochromic device 400 witha particle in the ion conducting layer causing a localized defect in thedevice. Electrochromic device 400 includes the same components asdepicted in FIG. 2 for electrochromic device 200. In the ion conductinglayer 208 of electrochromic device 400, however, there is a conductiveparticle 402 or other artifact causing a defect. Conductive particle 402results in a short between electrochromic layer 206 and counterelectrode layer 210. This short does not allow the flow of ions betweenelectrochromic layer 206 and counter electrode layer 210, insteadallowing electrons to pass locally between the layers, resulting in atransparent region 404 in the electrochromic layer 206 and a transparentregion 406 in the counter electrode layer 210 when the remainder oflayers 210 and 206 are in the colored state. That is, if electrochromicdevice 400 is in the colored state, conductive particle 402 rendersregions 404 and 406 of the electrochromic device unable to enter intothe colored state. Sometimes the defect regions are referred to as“constellations” because they appear as a series of bright spots (orstars) against a dark background (the remainder of the device being inthe colored state). Humans will naturally direct their attention to theconstellations and often find them distracting or unattractive.

FIG. 5A is a schematic cross-section of an electrochromic device 500with a particle 502 or other debris on conductive layer 204 prior todepositing the remainder of the electrochromic stack. Electrochromicdevice 500 includes the same components as electrochromic device 200.Particle 502 causes the layers in the electrochromic stack 220 to bulgein the region of particle 502, due to conformal layers 206-210 beingdeposited sequentially over particle 502 as depicted (in this example,layer 214 has not yet been deposited). While not wishing to be bound bya particular theory, it is believed that layering over such particles,given the relatively thin nature of the layers, can cause stress in thearea where the bulges are formed. More particularly, in each layer,around the perimeter of the bulged region, there can be defects in thelayer, e.g. in the lattice arrangement or on a more macroscopic level,cracks or voids. One consequence of these defects would be, for example,an electrical short between electrochromic layer 206 and counterelectrode layer 210 or loss of ion conductivity in layer 208. Thesedefects are not depicted in FIG. 5A, however.

Referring to FIG. 5B, another consequence of defects caused by particle502 is called a “pop-off.” In this example, prior to deposition ofconductive layer 214, a portion above the conductive layer 204 in theregion of particle 502 breaks loose, carrying with it portions ofelectrochromic layer 206, ion conducting layer 208, and counterelectrode layer 210. The “pop-off” is piece 504, which includes particle502, a portion of electrochromic layer 206, as well as ion conductinglayer 208 and counter electrode layer 210. The result is an exposed areaof conductive layer 204. Referring to FIG. 5C, after pop-off and onceconductive layer 214 is deposited, an electrical short is formed whereconductive layer 214 comes in contact with conductive layer 204. Thiselectrical short would leave a transparent region in electrochromicdevice 500 when it is in the colored state, similar in appearance to thedefect created by the short described above in relation to FIG. 4.

Pop-off defects due to particles or debris on substrate 202 or 204 (asdescribed above), on ion conducting layer 208, and on counterelectrodelayer 210 may also occur, causing pinhole defects when theelectrochromic device is in the colored state. Also, if particle 502 islarge enough and does not cause a pop-off, it might be visible whenelectrochromic device 500 is in the bleached state.

The electrochromic devices in embodiments of the invention are alsoscalable to substrates smaller or larger than architectural glass. Anelectrochromic stack can be deposited onto substrates that are a widerange of sizes, up to about 12 inches by 12 inches, or even 80 inches by120 inches. The capability of manufacturing electrochromic devices of 20by 20 inches allows the manufacture of electrochromic architecturalglass for many applications.

Even very small defects, ones that do not create noticeable points oflight or constellations, can cause serious performance problems. Forexample, small shorts, particularly multiple instances of them in arelatively small area, can cause a relatively large leakage current. Asa result, there may be a large local potential drop which prevents theelectrochromic device from switching in the vicinity of the leakagecurrent.

Hence small defects can limit the scalability of electrochromic devicesand sometimes preclude deployment on architectural glass.

In one embodiment, the number of visible pinhole defects is no greaterthan about 0.04 per square centimeter. In another embodiment, the numberof visible pinhole defects is no greater than about 0.02 per squarecentimeter, and in more specific embodiments, the number of such defectsis no greater than about 0.01 per square centimeter. Typically, thevisible short-type defects are individually treated after fabrication toleave short-related pinholes as the only visible defects. In oneembodiment, the number of visible short-related pinhole defects is nogreater than about 0.005 per square centimeter. In another embodiment,the number of visible short-related pinhole defects is no greater thanabout 0.003 per square centimeter, and in more specific embodiments, thenumber of such defects is no greater than about 0.001 per squarecentimeter. In one embodiment, the total number of visible defects,pinholes and short-related pinholes created from isolating visibleshort-related defects, is less than about 0.1 defects per squarecentimeter, in another embodiment less than about 0.08 defects persquare centimeter, in another embodiment less than about 0.045 defectsper square centimeter (less than about 450 defects per square meter ofwindow).

In some embodiments, the number of non-visible electrical short defectsresults in leakage currents of less than about 5 ρA/cm² at ±2V bias.These values apply across the entire face of the electrochromic device(i.e., there is no region of the device (anywhere on the device) havinga defect density greater than the recited value).

In some embodiments, the electrochromic device has no visible defectsgreater than about 1.6 mm in diameter (the largest transverse dimensionof the defect). In another embodiment, the device has no visible defectsgreater than about 0.5 mm in diameter, in another embodiment the devicehas no visible defects greater than about 100 μm in diameter.

In some embodiments, electrochromic glass is integrated into aninsulating glass unit (IGU). An insulating glass unit consists ofmultiple glass panes assembled into a unit, generally with the intentionof maximizing the thermal insulating properties of a gas contained inthe space formed by the unit while at the same time providing clearvision through the unit. Insulating glass units incorporatingelectrochromic glass would be similar to insulating glass unitscurrently known in the art, except for electrical leads for connectingthe electrochromic glass to voltage source. Due to the highertemperatures (due to absorption of radiant energy by an electrochromicglass) that electrochromic insulating glass units may experience, morerobust sealants than those used in conventional insulating glass unitsmay be necessary. For example, stainless steel spacer bars, hightemperature polyisobutylene (PIB), new secondary sealants, foil coatedPIB tape for spacer bar seams, and the like.

Method of Fabricating Electrochromic Windows

Deposition of the Electrochromic Stack

As mentioned in the summary above, one aspect of the invention is amethod of fabricating an electrochromic window. In a broad sense, themethod includes sequentially depositing on a substrate (i) anelectrochromic layer, (ii) an ion conducting layer, and (iii) a counterelectrode layer to form a stack in which the ion conducting layerseparates the electrochromic layer and the counter electrode layer. Thesequential deposition employs a single integrated deposition systemhaving a controlled ambient environment in which the pressure,temperature, and/or gas composition are controlled independently of anexternal environment outside of the integrated deposition system, andthe substrate does not leave the integrated deposition system at anytime during the sequential deposition of the electrochromic layer, theion conducting layer, and the counter electrode layer. (Examples ofintegrated deposition systems which maintain controlled ambientenvironments are described in more detail below in relation to FIGS.8A-E.) The gas composition may be characterized by the partial pressuresof the various components in the controlled ambient environment. Thecontrolled ambient environment also may be characterized in terms of thenumber of particles or particle densities. In certain embodiments, thecontrolled ambient environment contains fewer than 350 particles (ofsize 0.1 micrometers or larger) per m³. In certain embodiments, thecontrolled ambient environment meets the requirements of a class 100clean room (US FED STD 209E). In certain embodiments, the controlledambient environment meets the requirements of a class 10 clean room (USFED STD 209E). The substrate may enter and/or leave the controlledambient environment in a clean room meeting class 100 or even class 10requirements.

Typically, but not necessarily, this method of fabrication is integratedinto a multistep process for making an electrochromic window usingarchitectural glass as the substrate. For convenience, the followingdescription contemplates the method and its various embodiments in thecontext of a multistep process for fabricating an electrochromic window,but methods of the invention are not so limited. Electrochromic mirrorsand other devices may be fabricated using some or all of the operationsand approaches described herein.

FIG. 6A is a cross-sectional representation of an electrochromic windowdevice, 600, in accord with a multistep process such as that describedin relation to FIG. 7A. FIG. 7A depicts a process flow describing amethod, 700, of fabricating an electrochromic window which incorporateselectrochromic device 600. FIG. 6B is a top view of device 600 showingthe location of trenches cut into the device. Thus, FIGS. 6A-B and 7Awill be described together. One aspect of the description is anelectrochromic window including device 600 and another aspect of thedescription is a method, 700, of fabricating an electrochromic windowwhich includes device 600. Included in the following description aredescriptions of FIGS. 7B-7E. FIGS. 7B-7D depict specific methods offabricating an electrochromic stack which is part of device 600. FIG. 7Edepicts a process flow for a conditioning process used in fabricating,e.g., device 600.

FIG. 6A shows a specific example of an electrochromic device, 600, whichis fabricated starting with a substrate made of glass 605 whichoptionally has a diffusion barrier 610 coating and a first transparentconducting oxide (TCO) coating 615 on the diffusion barrier. Method 700employs a substrate that is, for example, float glass with sodiumdiffusion barrier and antireflective layers followed by a transparentconductive layer, for example a transparent conductive oxide 615. Asmentioned above, substrates suitable for devices of the inventioninclude glasses sold under the trademarks TEC Glass® by Pilkington ofToledo, Ohio, and SUNGATE® 300 and SUNGATE® 500 by PPG Industries, ofPittsburgh, Pa. The first TCO layer 615 is the first of two conductivelayers used to form the electrodes of electrochromic device 600fabricated on the substrate.

Method 700 begins with a cleaning process, 705, where the substrate iscleaned to prepare it for subsequent processing. As mentioned above, itis important to remove contaminants from the substrate because they cancause defects in the device fabricated on the substrate. One criticaldefect is a particle or other contaminant that creates a conductivepathway across the IC layer and thus shorts the device locally causingvisually discernable anomalies in the electrochromic window. One exampleof a cleaning process and apparatus suitable for the fabrication methodsof the invention is Lisec™ (a trade name for a glass washing apparatusand process available from (LISEC Maschinenbau Gmbh of Seitenstetten,Austria).

Cleaning the substrate may include mechanical scrubbing as well asultrasonic conditioning to remove unwanted particulates. As mentioned,particulates may lead to cosmetic flaws as well as local shorting withinthe device.

Once the substrate is cleaned, a first laser scribe process, 710, isperformed in order to remove a line of the first TCO layer on thesubstrate. In one embodiment, the resulting trench ablates through boththe TCO and the diffusion barrier (although in some cases the diffusionbarrier is not substantially penetrated). FIG. 6A depicts this firstlaser scribe trench, 620. A trench is scribed in the substrate acrossthe entire length of one side of the substrate in order to isolate anarea of the TCO, near one edge of the substrate, which will ultimatelymake contact with a first bus bar, 640, used to provide current to asecond TCO layer, 630, which is deposited on top of electrochromic (EC)stack 625 (which includes the electrochromic, ion conducting and counterelectrode layers as described above). FIG. 6B shows schematically (notto scale) the location of trench 620. In the depicted embodiment, thenon-isolated (main) portion of the first TCO layer, on the diffusionbarrier, ultimately makes contact with a second bus bar, 645. Isolationtrench 620 may be needed because, in certain embodiments, the method ofattaching the first bus bar to the device includes pressing it throughthe device stack layers after they are laid down (both on the isolatedportion of the first TCO layer and the main portion of the first TCOlayer). Those of skill in the art will recognize that other arrangementsare possible for providing current to the electrodes, in this case TCOlayers, in the electrochromic device. The TCO area isolated by the firstlaser scribe is typically an area along one edge of the substrate thatwill ultimately, along with the bus bars, be hidden when incorporatedinto the integrated glass unit (IGU) and/or window pane, frame orcurtain wall. The laser or lasers used for the first laser scribe aretypically, but not necessarily, pulse-type lasers, for examplediode-pumped solid state lasers. For example, the laser scribes can beperformed using a suitable laser from IPG Photonics (of OxfordMassachusetts), or from Ekspla (of Vilnius Lithuania).

The laser trench is dug along a side of the substrate from end to end toisolate a portion of the first TCO layer; the depth and width dimensionsof trench 620 made via first laser scribe 710 should be sufficient toisolate the first TCO layer from the bulk TCO once the device issubsequently deposited . The depth and width of the trench should besufficient to prevent any remaining particulates to short across thetrench. In one embodiment, the trench is between about 300 nm and 500 nmdeep and between about 20 μm and 50 μm wide. In another embodiment, thetrench is between about 350 nm and 450 nm deep and between about 30 μmand 45 μm wide. In another embodiment, the trench is about 400 nm deepand about 40 μm wide.

After the first laser scribe 710, the substrate is cleaned again(operation 715), typically but not necessarily, using cleaning methodsdescribed above. This second cleaning process is performed to remove anydebris caused by the first laser scribe. Once cleaning operation 715 iscomplete, the substrate is ready for deposition of EC stack 625. This isdepicted in process flow 700 as process 720. As mentioned above, themethod includes sequentially depositing on a substrate (i) an EC layer,(ii) an IC layer, and (iii) a CE layer to form a stack in which the IClayer separates the EC layer and the CE layer using a single integrateddeposition system having a controlled ambient environment in which thepressure and/or gas composition are controlled independently of anexternal environment outside of the integrated deposition system, andthe substrate does not leave the integrated deposition system at anytime during the sequential deposition of the EC layer, the IC layer, andthe CE layer. In one embodiment, each of the sequentially depositedlayers is physical vapor deposited. In general the layers of theelectrochromic device may be deposited by various techniques includingphysical vapor deposition, chemical vapor deposition, plasma enhancedchemical vapor deposition, and atomic layer deposition, to name a few.The term physical vapor deposition as used herein includes the fullrange of art understood PVD techniques including sputtering,evaporation, ablation, and the like. FIG. 7B depicts one embodiment ofprocess 720. First the EC layer is deposited on the substrate, process722, then the IC layer is deposited, process 724, then the CE layer,process 726. The reverse order of deposition is also an embodiment ofthe invention, that is, where the CE layer is deposited first, then theIC layer and then the EC layer. In one embodiment, each of theelectrochromic layer, the ion conducting layer, and the counterelectrode layer is a solid phase layer. In another embodiment, each ofthe electrochromic layer, the ion conducting layer, and the counterelectrode layer includes only inorganic material.

It should be understood that while certain embodiments are described interms of a counter electrode layer, an ion conductor layer, and anelectrochromic layer, any one or more of these layers may be composed ofone or more sub-layers, which may have distinct compositions, sizes,morphologies, charge densities, optical properties, etc. Further any oneor more of the device layers may have a graded composition or a gradedmorphology in which the composition or morphology, respectively, changesover at least a portion of the thickness of the layer. In one example,the concentration of a dopant or charge carrier varies within a givenlayer, at least as the layer is fabricated. In another example, themorphology of a layer varies from crystalline to amorphous. Such gradedcomposition or morphology may be chosen to impact the functionalproperties of the device. In some cases, additional layers may be addedto the stack. In one example a heat spreader layer is interposed betweenone or both TCO layers and the EC stack.

Also, as described above, the electrochromic devices of the inventionutilize ion movement between the electrochromic layer and the counterelectrode layer via an ion conducting layer. In some embodiments theseions (or neutral precursors thereof) are introduced to the stack as oneor more layers (as described below in more detail in relation to FIGS.7C and 7D) that eventually intercalate into the stack. In someembodiments these ions are introduced into the stack concurrently withone or more of the electrochromic layer, the ion conducting layer, andthe counter electrode layer. In one embodiment, where lithium ions areused, lithium is, e.g., sputtered along with the material used to makethe one or more of the stack layers or sputtered as part of a materialthat includes lithium (e.g., by a method employing lithium nickeltungsten oxide). In one embodiment, the IC layer is deposited viasputtering a lithium silicon aluminum oxide target. In anotherembodiment, the Li is cosputtered along with silicon aluminum in orderto achieve the desired film.

Referring again to process 722 in FIG. 7B, in one embodiment, depositingthe electrochromic layer comprises depositing WO,, e.g. where x is lessthan 3.0 and at least about 2.7. In this embodiment, the WO, has asubstantially nanocrystalline morphology. In some embodiments, theelectrochromic layer is deposited to a thickness of between about 200 nmand 700 nm. In one embodiment, depositing the electrochromic layerincludes sputtering tungsten from a tungsten containing target. In onesuch embodiment, a metallic tungsten (or tungsten alloy) target is used.In another embodiment (which may also employ a metallic tungsten target)the sputter gas is an inert gas (e.g., argon or xenon) with some oxygencontaining gas (e.g., molecular or atomic oxygen) present. This is partof the controlled ambient environment that may be present in adeposition chamber or a station within a larger chamber. In oneembodiment, the gas composition contains between about 30% and about100% oxygen, in another embodiment between about 50% and about 80%oxygen, in yet another embodiment between about 65% and about 75%oxygen. In one embodiment, the tungsten containing target containsbetween about 80% and 100% (by weight) tungsten, in another embodimentbetween about 95% and 100% tungsten, and in yet another embodimentbetween about 99% and 100% tungsten. In one embodiment, the gascomposition is about 70% oxygen/30% argon and the target is metallictungsten of a purity of between about 99% and 100%. In anotherembodiment a tungsten oxide W(0) ceramic target is sputtered with, e.g.,argon. The pressure in the deposition station or chamber, in oneembodiment, is between about 1 and about 75 mTorr, in another embodimentbetween about 5 and about 50 mTorr, in another embodiment between about10 and about 20 mTorr. In one embodiment, the substrate temperature forprocess 722 is between about 100° C. and about 500° C., in anotherembodiment between about 100° C. and about 300° C., and in anotherembodiment between about 150° C. and about 250° C. The substratetemperature may be measured in situ by, e.g., a thermocouple such as aninfra-red thermo-couple (IR t/c). In one embodiment, the power densityused to sputter the EC target is between about 2 Watts/cm² and about 50Watts/cm² (determined based on the power applied divided by the surfacearea of the target); in another embodiment between about 10 Watts/cm²and about 20 Watts/cm²; and in yet another embodiment between about 15Watts/cm² and about 20 Watts/cm². In some embodiments, the powerdelivered to effect sputtering is provided via direct current (DC). Inother embodiments, pulsed DC/AC reactive sputtering is used. In oneembodiment, where pulsed DC/AC reactive sputtering is used, thefrequency is between about 20 kHz and about 400 kHz, in anotherembodiment between about 20 kHz and about 50 kHz, in yet anotherembodiment between about 40 kHz and about 50 kHz, in another embodimentabout 40 kHz. The above conditions may be used in any combination withone another to effect deposition of a high quality tungsten oxideelectrochromic layer.

In one embodiment, in order to normalize the rate of deposition oftungsten, multiple targets are used so as to obviate the need forinappropriately high power (or other inappropriate adjustment to desiredprocess conditions) to increase deposition rate. The distance betweenthe target and the substrate may also be important. In one embodiment,the distance between the target (cathode or source) to the substratesurface is between about 35 mm and about 150 mm; in another embodimentbetween about 45 mm and about 130 mm; and in another embodiment betweenabout 70 mm and about 100 mm.

It should be understood that while deposition of the EC layer isdescribed in terms of sputtering from a target, other depositiontechniques are employed in some embodiments. For example, chemical vapordeposition, atomic layer deposition, and the like may be employed. Eachof these techniques, along with PVD, has its own form of material sourceas is known to those of skill in the art.

Referring again to FIG. 7B, operation 724, once the EC layer isdeposited, the IC layer is deposited. In one embodiment, depositing theion conducting layer includes depositing a material selected from thegroup consisting of a tungsten oxide, a tantalum oxide, a niobium oxide,and a silicon aluminum oxide. In another embodiment, depositing the ionconducting layer includes sputtering a target including between about 2%and 20% by weight of aluminum (remainder silicon) in an oxygencontaining environment to produce a layer of silicon aluminum oxide. Ina more specific embodiment, the target is between about 5% and about 10%aluminum in silicon, in another embodiment, between about 7% and about9% aluminum in silicon. In one embodiment, the gas composition containsbetween about 15% and about 70% oxygen, in another embodiment betweenabout 20% and about 50% oxygen, in yet another embodiment between about25% and about 45% oxygen, in another embodiment about 35% oxygen. Inanother embodiment, depositing the ion conducting layer includesdepositing the ion conducting layer to a thickness of between about 10and 100 nm. In yet another embodiment, depositing the ion conductinglayer includes depositing the ion conducting layer to a thickness ofbetween about 20 and 50 nm. In one embodiment, the power density used tosputter the IC target is between about 1 Watts/cm² and about 20Watts/cm² (determined based on the power applied divided by the surfacearea of the target); in another embodiment between about 5 Watts/cm² andabout 7 Watts/cm²; and in yet another embodiment between about 6Watts/cm² and about 6.5 Watts/cm². In some embodiments, the powerdelivered to effect sputtering is provided via direct current (DC). Inother embodiments, pulsed DC/AC reactive sputtering is used. In oneembodiment, where pulsed DC/AC reactive sputtering is used, thefrequency is between about 20 kHz and about 400 kHz, in anotherembodiment between about 20 kHz and about 50 kHz, in yet anotherembodiment between about 40 kHz and about 50 kHz, in another embodimentabout 40 kHz. The pressure in the deposition station or chamber, in oneembodiment, is between about 5 mTorr and about 40 mTorr, in anotherembodiment between about 10 mTorr and about 30 mTorr, in anotherembodiment about 20 mTorr. In one embodiment, the substrate temperatureranges for operation 724 are between about 20° C. and about 200° C., insome embodiments between about 20° C. and about 150° C., and it yetstill other embodiments between about 25° C. and about 100° C. The aboveconditions may be used in any combination with one another to effectdeposition of a high quality ion conducting layer.

Referring again to FIG. 7B, operation 726, after the IC layer isdeposited, the CE layer is deposited. In one embodiment, depositing thecounter electrode layer includes depositing a layer of nickel tungstenoxide (NiWO), preferably amorphous NiWO. In a specific embodiment,depositing the counter electrode layer includes sputtering a targetincluding about 30% (by weight) to about 70% of tungsten in nickel in anoxygen containing environment to produce a layer of nickel tungstenoxide. In another embodiment the target is between about 40% and about60% tungsten in nickel, in another embodiment between about 45% andabout 55% tungsten in nickel, and in yet another embodiment about 51%tungsten in nickel. In one embodiment, the gas composition containsbetween about 30% and about 100% oxygen, in another embodiment betweenabout 80% and about 100% oxygen, in yet another embodiment between about95% and about 100% oxygen, in another embodiment about 100% oxygen. Inone embodiment, the power density used to sputter the CE target isbetween about 2 Watts/cm² and about 50 Watts/cm² (determined based onthe power applied divided by the surface area of the target); in anotherembodiment between about 5 Watts/cm² and about 20 Watts/cm²; and in yetanother embodiment between about 8 Watts/cm² and about 10 Watts/cm², inanother embodiment about 8 Watts/cm². In some embodiments, the powerdelivered to effect sputtering is provided via direct current (DC). Inother embodiments, pulsed DC/AC reactive sputtering is used. In oneembodiment, where pulsed DC/AC reactive sputtering is used, thefrequency is between about 20 kHz and about 400 kHz, in anotherembodiment between about 20 kHz and about 50 kHz, in yet anotherembodiment between about 40 kHz and about 50 kHz, in another embodimentabout 40 kHz. The pressure in the deposition station or chamber, in oneembodiment, is between about 1 and about 50 mTorr, in another embodimentbetween about 20 and about 40 mTorr, in another embodiment between about25 and about 35 mTorr, in another embodiment about 30 mTorr. In somecases, a nickel tungsten oxide NiWO ceramic target is sputtered with,e.g., argon and oxygen. In one embodiment, the NiWO is between about 15%(atomic) Ni and about 60% Ni; between about 10% W and about 40% W; andbetween about 30% 0 and about 75% 0. In another embodiment, the NiWO isbetween about 30% (atomic) Ni and about 45% Ni; between about 10% W andabout 25% W; and between about 35% 0 and about 50% 0. In one embodiment,the NiWO is about 42% (atomic) Ni, about 14% W, and about 44% 0. Inanother embodiment, depositing the counter electrode layer includesdepositing the counter electrode layer to a thickness of between about150 and 350 nm; in yet another embodiment between about 200 and about250 nm thick. The above conditions may be used in any combination withone another to effect deposition of a high quality NiWO layer.

In one embodiment, in order to normalize the rate of deposition of theCE layer, multiple targets are used so as to obviate the need forinappropriately high power (or other inappropriate adjustment to desiredprocess conditions) to increase deposition rate. In one embodiment, thedistance between the CE target (cathode or source) to the substratesurface is between about 35 mm and about 150 mm; in another embodimentbetween about 45 mm and about 130 mm; and in another embodiment betweenabout 70 mm and about 100 mm.

It should be understood that while the order of deposition operations isdepicted in FIG. 7B (and implied in FIG. 6A) to be first EC layer,second IC layer, and finally CE layer, the order can be reversed invarious embodiments. In other words, when as described herein“sequential” deposition of the stack layers is recited, it is intendedto cover the following “reverse” sequence, first CE layer, second IClayer, and third EC layer, as well the “forward” sequence describedabove. Both the forward and reverse sequences can function as reliablehigh-quality electrochromic devices. Further, it should be understoodthat conditions recited for depositing the various EC, IC, and CEmaterials recited here, are not limited to depositing such materials.Other materials may, in some cases, be deposited under the same orsimilar conditions. Further, non-sputtering deposition conditions may beemployed in some embodiments to create the same or similar depositedmaterials as those described in the context of FIGS. 6 and FIGS. 7.

Since the amount of charge each of the EC and the CE layers can safelyhold varies, depending on the material used, the relative thickness ofeach of the layers may be controlled to match capacity as appropriate.In one embodiment, the electrochromic layer includes tungsten oxide andthe counter electrode includes nickel tungsten oxide, and the ratio ofthicknesses of the electrochromic layer to the counter electrode layeris between about 1.7:1 and 2.3:1, or between about 1.9:1 and 2.1:1 (withabout 2:1 being a specific example).

Referring again to FIG. 7B, operation 720, after the CE layer isdeposited, the EC stack is complete. It should be noted that in FIG. 7A,process operation 720 which refers to “depositing stack” means in thiscontext, the EC stack plus the second TCO layer (sometimes referred toas the “ITO” when indium tin oxide is used to make the second TCO).Generally “stack” in this description refers to the EC-IC-CE layers;that is, the “EC stack.” Referring again to FIG. 7B, in one embodiment,represented by process 728, a TCO layer is deposited on the stack.Referring to FIG. 6A, this would correspond to second TCO layer 630 onEC stack 625. Process flow 720 is finished once process 728 is complete.Typically, but not necessarily, a capping layer is deposited on the ECstack. In some embodiments, the capping layer is SiA1O, similar to theIC layer. In some embodiments, the capping layer is deposited bysputtering, similar to the conditions under which the IC layer isdeposited. The thickness of a capping layer is typically about 30 nm to100 nm. In one embodiment, depositing the layer of transparentconductive oxide is performed under conditions whereby the transparentconductive oxide has a sheet resistance of between about 10 and 30ohms/square. In one embodiment as discussed above, the first and secondTCO layers are of matched sheet resistance for optimum efficiency of theelectrochromic device. Ideally the first TCO layer's morphology shouldbe smooth for better conformal layers in the deposited stack. In oneembodiment, a substantially uniform TCO layer varies only about ±10% ineach of the aforementioned thickness ranges. In another embodiment, asubstantially uniform TCO layer varies only about ±5% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform TCO layer varies only about ±2% in each of the aforementionedthickness ranges.

In certain specific embodiments, the second TCO layer 630 is depositedusing some or all of the following conditions. The recited conditionsmay be employed to form a thin, low-defect layer of indium tin oxide bysputtering a target containing indium oxide in tin oxide, e.g. with anargon sputter gas with or without oxygen. In one embodiment, thethickness of the TCO layer is between about 5 nm and about 10,000 nm, inanother embodiment between about 10 nm and about 1,000 nm, In yetanother embodiment between about 10 nm and about 500 nm. In oneembodiment, the substrate temperature for operation 728 is between about20 and about 300° C., in another embodiment between about 20 and about250° C., and in another embodiment between about 80 and about 225° C. Inone embodiment, depositing the TCO layer includes sputtering a targetincluding between about 80% (by weight) to about 99% of In₂O₃ andbetween about 1% and about 20% SnO₂ using an inert gas, optionally withoxygen. In a more specific embodiment, the target is between about 85%(by weight) to about 97% of In₂O₃ and between about 3% and about 15%SnO₂. In another embodiment, the target is about 90% of In₂O₃ and about10% SnO₂. In one embodiment, the gas composition contains between about0.1% and about 3% oxygen, in another embodiment between about 0.5% andabout 2% oxygen, in yet another embodiment between about 1% and about1.5% oxygen, in another embodiment about 1.2% oxygen. In one embodiment,the power density used to sputter the TCO target is between about 0.5Watts/cm² and about 10 Watts/cm² (determined based on the power applieddivided by the surface area of the target); in another embodimentbetween about 0.5 Watts/cm² and about 2 Watts/cm²; and in yet anotherembodiment between about 0.5 Watts/cm² and about 1 Watts/cm², in anotherembodiment about 0.7 Watts/cm². In some embodiments, the power deliveredto effect sputtering is provided via direct current (DC). In otherembodiments, pulsed DC/AC reactive sputtering is used. In oneembodiment, where pulsed DC/AC reactive sputtering is used, thefrequency is between about 20 kHz and about 400 kHz, in anotherembodiment between about 50 kHz and about 100 kHz, in yet anotherembodiment between about 60 kHz and about 90 kHz, in another embodimentabout 80 kHz. The pressure in the deposition station or chamber, in oneembodiment, is between about 1 and about 10 mTorr, in another embodimentbetween about 2 and about 5 mTorr, in another embodiment between about 3and about 4 mTorr, in another embodiment about 3.5 mTorr. In oneembodiment, the indium tin oxide layer is between about 20% (atomic) Inand about 40% In; between about 2.5% Sn and about 12.5% Sn; and betweenabout 50% 0 and about 70% 0; in another embodiment, between about 25% Inand about 35% In; between about 5.5% Sn and about 8.5% Sn; and betweenabout 55% 0 and about 65% 0; and in another embodiment, about 30% In,about 8% Sn; and about 62% 0. The above conditions may be used in anycombination with one another to effect deposition of a high qualityindium tin oxide layer.

As mentioned, the EC stack is fabricated in an integrated depositionsystem where the substrate does not leave the integrated depositionsystem at any time during fabrication of the stack. In one embodiment,the second TCO layer is also formed using the integrated depositionsystem where the substrate does not leave the integrated depositionsystem during deposition of the EC stack and the TCO layer. In oneembodiment, all of the layers are deposited in the integrated depositionsystem where the substrate does not leave the integrated depositionsystem during deposition; that is, in one embodiment the substrate is aglass sheet and a stack including the EC layer, the IC layer and the CElayer, sandwiched between a first and a second TCO layer, is fabricatedon the glass where the glass does not leave the integrated depositionsystem during deposition. In another implementation of this embodiment,the substrate is glass with a diffusion barrier deposited prior to entryin the integrated deposition system. In another implementation thesubstrate is glass and the diffusion barrier, a stack including the EClayer, the IC layer and the CE layer, sandwiched between a first and asecond TCO layer, are all deposited on the glass where the glass doesnot leave the integrated deposition system during deposition.

While not wishing to be bound by theory, it is believed that prior artelectrochromic devices suffered from high defectivity for variousreasons, one of which is the integration of unacceptably high numbers ofparticles into the IC layer during fabrication. Care was not taken toensure that each of the EC layer, IC layer, and CE layer were depositedin a single integrated deposition apparatus under a controlled ambientenvironment. In one process, the IC layer is deposited by a sol gelprocess, which is necessarily performed apart from other vacuumintegrated processes. In such process, even if the EC layer and/or theCE layer are deposited in a controlled ambient environment, therebypromoting high quality layers, the substrate would have to be removedfrom the controlled ambient environment to deposit the IC layer. Thiswould normally involve passing the substrate through a load lock (fromvacuum or other controlled ambient environment to an externalenvironment) prior to formation of the IC layer. Passage through a loadlock typically introduces numerous particles onto the substrate.Introducing such particles immediately before the IC layer is depositedgreatly increases the likelihood that defects will form in the criticalIC layer. Such defects lead to bright spots or constellations asdiscussed above.

As mentioned above, lithium may be provided with the EC, CE and/or IClayers as they are formed on the substrate. This may involve, forexample, co-sputtering of lithium together with the other materials of agiven layer (e.g., tungsten and oxygen). In certain embodimentsdescribed below the lithium is delivered via a separate process andallowed to diffuse or otherwise incorporate into the EC, CE and/or IClayers.

Direct Lithiation of the Electrochromic Stack

In some embodiments, as mentioned above, intercalation of lithium ionsis responsible for switching the optical state of an electrochromicdevice stack. It should be understood that the needed lithium may beintroduced to the stack by various means. For example, lithium may beprovided to one or more of these layers concurrently with the depositionof the material of the layer (e.g., concurrent deposition of lithium andtungsten oxide during formation of the EC layer). In some cases,however, the process of FIG. 7B may be punctuated with one or moreoperations for delivering lithium to the EC layer, the IC layer, and/orthe CE layer. For example, lithium may also be introduced via one ormore separate lithiation steps in which elemental lithium is deliveredwithout substantial deposition of other material. Such lithiationstep(s) may take place after deposition of the EC layer, the IC layer,and/or the CE layer. Alternatively (or in addition), one or morelithiation steps may take intermediate between steps performed todeposit a single layer. For example, a counter electrode layer may bedeposited by first depositing a limited amount of nickel tungsten oxide,followed by directly depositing lithium, and then concluded bydepositing additional amounts of nickel tungsten oxide. Such approachesmay have certain advantages such as better separating the lithium fromthe ITO (or other material of a conductive layer) which improvesadhesion and prevents undesirable side reactions. One example of a stackformation process employing a separate lithiation operation is presentedin FIG. 7C. In certain cases, the lithiation operation(s) takes placeduring while the deposition of a given layer is temporarily halted toallow lithium to be introduced before deposition of the layer iscompleted.

FIG. 7C depicts a process flow, 720 a, for depositing the stack onto asubstrate in a manner analogous to process 720 of FIG. 7A. Process flow720 a includes depositing an EC layer, operation 722, depositing an IClayer, operation 724, and depositing a CE layer, operation 726, asdescribed in relation to FIG. 7B. However, process flow 720 a differsfrom 720 by the addition of lithiation operations 723 and 727. In oneembodiment, the lithium is physical vapor deposited using an integrateddeposition system where the substrate does not leave the integrateddeposition system at any time during the sequential deposition of theelectrochromic layer, the ion conducting layer, the counter electrodelayer, and the lithium.

In certain embodiments, lithium is deposited using a high voltagelithium cathode since there are not many secondary electron emissionsduring lithium sputtering. In some embodiments, the power delivered toeffect sputtering is provided via direct current (DC). In otherembodiments, pulsed DC/AC reactive sputtering is used. In oneembodiment, where pulsed DC/AC reactive sputtering is used, thefrequency is between about 20 kHz and about 400 kHz, in anotherembodiment between about 100 kHz and about 300 kHz, in yet anotherembodiment between about 200 kHz and about 250 kHz, in anotherembodiment about 220 kHz. A lithium target is used. In one embodimentthe target is between about 80% (by weight) and 100% Li, in anotherembodiment between about 90% and about 99% Li, in another embodimentabout 99% Li. Typically, due to the extreme reactivity of elementallithium, lithiation is performed in an inert environment (e.g., argonalone). The power density used to sputter the lithium target is betweenabout 1 Watts/cm² and about 10 Watts/cm² (determined based on thedeposition surface area of the substrate); in another embodiment betweenabout 2 Watts/cm² and about 4 Watts/cm²; in yet another embodimentbetween about 2.5 Watts/cm² and about 3 Watts/cm²; in another embodimentabout 2.7 Watts/cm². In one embodiment the lithium sputtering is done ata pressure of between about 1 and about 20 mTorr, in another embodimentbetween about 5 and about 15 mTorr, in another embodiment about 10mTorr. The above conditions may be used in any combination with oneanother to effect deposition of a high quality lithiation process .

In one embodiment, lithium is deposited on both the EC layer and the CElayer as depicted in dual lithiation process 720 a. After the EC layeris deposited as described above, operation 722, lithium is sputtered onthe EC layer; see operation 723. Thereafter, the IC layer is deposited,operation 724, followed by the CE layer, operation 726. Then lithium isdeposited on the CE layer; see operation 727. In one embodiment where,e.g., the EC layer is tungsten oxide and about twice as thick as anickel tungsten oxide CE layer, the total amount of lithium added to thestack is proportioned between the EC layer and the CE layer in a ratioof about 1:3 to 2:3; that is, the EC layer is sputtered with ⅓ of thetotal lithium and the CE layer with about ⅔ of the total lithium addedto the stack. In a specific embodiment, the lithium added to the stackis proportioned between the EC layer and the CE layer in a ratio ofabout 1:2.

In the depicted dual lithiation method, both the EC layer and the CElayer are lithiated. Without wishing to be bound by theory, it isbelieved that by delivering lithium to both the EC layer and the CElayer, performance and yield are improved. The relatively large volumechange due to insertion of lithium ions into a depleted layer (asfabricate) during initial equilibration (from a single lithiation on oneside of the IC layer) is avoided. These volume changes, which arereported to be as large as 6% in electrochromically active tungstenoxide initially devoid of lithium, can produce cracking and delaminationof the stack layers. Therefore, improvements can be realized byfabricating the stack with a dual lithiation process as describedherein, which results in less than 6% volume change in theelectrochromic layer. In certain embodiments, the volume change is atmost about 4%.

In one embodiment of the dual lithiation method, as explained above, theEC layer is treated with sufficient lithium to satisfy the requirementsof the EC material irreversibly bound lithium (to, e.g., compensate“blind charge”). The lithium needed for reversible cycling is added tothe CE layer (which also may have a blind charge). In certainembodiments, the lithium needed to compensate the blind charge can betitrated by monitoring optical density of the EC layer as lithium isadded since the EC layer will not substantially change color untilsufficient lithium has been added to fully compensate the blind charge.

One of ordinary skill in the art would appreciate that because metalliclithium is pyrophoric, i.e. highly reactive with moisture and oxygen,that lithiation methods described herein where lithium might be exposedto oxygen or moisture are performed either under vacuum, inertatmosphere or both. The controlled ambient environment of apparatus andmethods of the invention provides flexibility in lithium depositions,particularly where there are multiple lithiation steps. For example,where lithiation is performed in a titration process and/or amongmultiple steps in a stack layering, the lithium can be protected fromexposure to oxygen or moisture.

In certain embodiments, the lithiation is performed at a rate sufficientto prevent formation of a substantial thickness of free lithium on theEC layer surface. In one embodiment, during lithiation of the EC layer,lithium targets are spaced sufficiently to give time for lithium todiffuse into the EC layer. Optionally, the substrate (and hence the EClayer) is heated to between about 100° C. and about 150° C. to enhancediffusion of lithium into the EC layer. Heating may be done separatelyor in combination with target spacing and substrate translation past thetarget(s). In some cases, the substrate is moved back and forth in frontof a sputtered lithium target in order to slow the delivery of lithiumto the substrate and prevent accumulation of free metallic lithium onthe stack surface.

In some cases, the lithiation processes are performed with isolationprotocols in place. In one example, isolation protocols are performedwith isolation valves within the integrated deposition system. Forexample, once a substrate is moved into a lithiation station, isolationvalves shut to cut off the substrate from other stations and forexample, flush with argon or evacuate to prepare for the lithiation. Inanother embodiment, the isolation is achieved by manipulating thecontrolled ambient environment, e.g., by creating a flow dynamic in thecontrolled ambient environment via differential pressures in alithiation station of the integrated deposition system such that thelithium deposition is sufficiently isolated from other processes in theintegrated deposition system. In another embodiment, a combination ofthe aforementioned conditions are used. For example valves can partiallyclose (or the lithiation station can be configured so that the substrateentry and/or exit ports are minimized) and one or more flow dynamics areused to further isolate the lithiation process from adjoining processes.Referring again to FIG. 7C, after the dual lithiation process asdescribed in operations 722-727, the (second) TCO layer is deposited(operation 728) as described above.

FIG. 7D depicts another process flow, 720 b, for depositing the stackonto a substrate. The process is analogous to process flow 700 of FIG.7A. Process flow 720 b includes depositing an EC layer (operation 722)depositing an IC layer (operation 724) and depositing a CE layer(operation 726) as described in relation to FIG. 7B. However, processflow 720 b differs from 720 because there is an intervening lithiationoperation 727. In this embodiment of the process of stack deposition,all the required lithium is added by delivering lithium to the CE layerand allowing the lithium to intercalate into the EC layer via diffusionthrough the IC layer during and/or after stack fabrication. Asmentioned, this may not avoid larger volume changes associated withloading all the required lithium for the device on one side of the IClayer, as the dual lithiation process 720 a does, but it has theadvantage of having one less lithium delivery step.

Multistep Thermochemical Conditioning

Referring again to FIG. 7A, once the stack is deposited, the device issubjected to a multistep thermo-chemical conditioning (MTC) process (seeblock 730). Typically, the MTC process is performed only after alllayers of the electrochromic stack have been formed. Some embodiments ofthe MTC process 730 are depicted in more detail in FIG. 7E. Note thatthe MTC process can be conducted entirely ex situ, i.e., outside of theintegrated deposition system used to deposit the stack, or at leastpartially in situ, i.e., inside the deposition system without e.g.breaking vacuum or otherwise moving the substrate outside the controlledambient environment used to fabricate the stack. In certain embodiments,the initial portions of the MTC process are performed in situ, and laterportions of the process are performed ex situ. In certain embodiments,portions of the MTC are performed prior to deposition of certain layers,for example, prior to deposition of the second TCO layer.

Referring to FIG. 7E, and in accordance with certain embodiments, thedevice is first thermally treated under non-reactive conditions (e.g.,under an inert gas). See block 732. In a specific embodiment, the deviceis heated at a temperature of between about 200° C. and about 350° C.for between about 5 minutes and about 30 minutes. In certainembodiments, operation 732 is conducted at low pressure or vacuum.Without wishing to be bound by theory, it is believed that inert gasheating moves any excess lithium from the EC layer to the CE layer, thuscharging the CE layer with lithium (as indicated in some cases by the CElayer's transparency increasing during this process). Next, the deviceis subjected to a thermal treatment under reactive conditions. See block734. In some embodiments, this involves annealing the device in anoxidizing atmosphere (e.g., oxygen and inert gas at about 10-50 mTorr).In specific embodiments, the anneal is conducted at higher pressuresthan the non-reactive thermal processing step (732). In a specificembodiment, the device is heated at a temperature of between about 200°C. and about 350° C. for between about 3 minutes and about 20 minutes.While not wishing to be bound to theory, it is believed that theoxidative anneal process improves the conductivity of the NiWO byforming a matrix of Li₂WO₄ (which is a very good lithium ion conductor)that encapsulates individual NiWO grains. NiWO embedded in a highlyionically conductive matrix facilitates rapid optical transitions.

Optionally, after the oxidative anneal, the device is heated in air (exsitu). In one embodiment, the device is heated at between about 150° C.and about 500° C. for between about 1 minutes and about 60 minutes, inanother embodiment at between about 200° C. and about 400° C. forbetween about 5 minutes and about 30 minutes, process 736. It should beunderstood that the MTC process may include two, three, or more separateand distinct operations. The three operations described here areprovided solely for purposes of exemplifying the process. Further, theprocess conditions presented here are appropriate for architecturalglass, but may have to be scaled for other applications, recognizingthat the time to heat a device is dependent upon the size of the device.After the MTC process is complete, the device is ready for furtherprocessing.

As mentioned above, additional layers may be needed for improved opticalperformance (e.g. anti-reflectives), durability (due to physicalhandling), hermeticity, and the like. Addition of one or more of theselayers is meant to be included in additional embodiments to thosedescribed above.

Fabrication Process for Completion of the Device

Again referring to FIG. 7A, a second laser scribe (block 740) isperformed. Laser scribe 740 is performed across the length of thesubstrate near the outer edge of the stack, on the two sides of thesubstrate perpendicular to the first laser scribe. FIG. 6B shows thelocation of the trenches, 626, formed by laser scribe 740. This scribeis also performed all the way through the first TCO (and diffusionbarrier if present) to the substrate in order to further isolate theisolated portion of the first TCO layer (where the first bus bar will beconnected) and to isolate the stack coating at the edges (e.g. near amask) to minimize short circuits due to deposition roll off of the stacklayers. In one embodiment, the trench is between about 25 μm and 75 μmdeep and between about 100 μm and 300 μm wide. In another embodiment,the trench is between about 35 μm and 55 μm deep and between about 150μm and 250 μm wide. In another embodiment, the trench is about 50 μmdeep and about 150 μm wide.

Next, a third laser scribe, 745, is performed along the perimeter of thestack near the edge of the substrate opposite the first laser scribe andparallel to the first laser scribe. This third laser scribe is only deepenough to isolate the second TCO layer and the EC stack, but not cutthrough the first TCO layer. Referring to FIG. 6A, laser scribe 745forms a trench, 635, which isolates the uniform conformal portions ECstack and second TCO from the outermost edge portions which can sufferfrom roll off (e.g. as depicted in FIG. 6A, the portion of layers 625and 630 near area 650 isolated by cutting trench 635) and thus causeshorts between the first and second TCO layers in region 650 near wherethe second bus bar will be attached. Trench 635 also isolates roll offregions of the second TCO from the second bus bar. Trench 635 is alsodepicted in FIG. 6B. One of ordinary skill in the art would appreciatethat laser scribes 2 and 3, although scribed at different depths, couldbe done in a single process whereby the laser cutting depth is variedduring a continuous path around the three sides of the substrate asdescribed. First at a depth sufficient to cut past the first TCO (andoptionally the diffusion barrier) along a first side perpendicular tothe first laser scribe, then at a depth sufficient only to cut throughto the bottom of the EC stack along the side opposite and parallel tothe first laser scribe, and then again at the first depth along thethird side, perpendicular to the first laser scribe.

Referring again to process 700, in FIG. 7A, after the third laserscribe, the bus bars are attached, process 750. Referring to FIG. 6A,bus bar 1, 640, and bus bar 2, 645, are attached. Bus bar 1 is oftenpressed through the second TCO and EC stack to make contact with thesecond TCO layer, for example via ultrasonic soldering. This connectionmethod necessitates the laser scribe processes used to isolate theregion of the first TCO where bus bar 1 makes contact. Those of ordinaryskill in the art will appreciate that other means of connecting bus bar1 (or replacing a more conventional bus bar) with the second TCO layerare possible, e.g., screen and lithography patterning methods. In oneembodiment, electrical communication is established with the device'stransparent conducting layers via silk screening (or using anotherpatterning method) a conductive ink followed by heat curing or sinteringthe ink. When such methods are used, isolation of a portion of the firstTCO layer is avoided. By using process flow 700, an electrochromicdevice is formed on a glass substrate where the first bus bar is inelectrical communication with second TCO layer 630 and the second busbar is in electrical contact with first TCO layer 615. In this way, thefirst and second TCO layers serve as electrodes for the EC stack.

Referring again to FIG. 7A, after the bus bars are connected, the deviceis integrated into an IGU, process 755. The IGU is formed by placing agasket or seal (e.g. made of PVB (polyvinyl butyral), PIB or othersuitable elastomer) around the perimeter of the substrate. Typically,but not necessarily, a desiccant is included in the IGU frame or spacerbar during assembly to absorb any moisture. In one embodiment, the sealsurrounds the bus bars and electrical leads to the bus bars extendthrough the seal. After the seal is in place, a second sheet of glass isplaced on the seal and the volume produced by the substrate, the secondsheet of glass and the seal is filled with inert gas, typically argon.Once the IGU is complete, process 700 is complete. The completed IGU canbe installed in, for example, a pane, frame or curtain wall andconnected to a source of electricity and a controller to operate theelectrochromic window.

In addition to the process steps described in relation to the methodsabove, an edge deletion step or steps may be added to the process flow.Edge deletion is part of a manufacturing process for integrating theelectrochromic device into, e.g. a window, where the roll off (asdescribed in relation to FIG. 6A) is removed prior to integration of thedevice into the window. Where unmasked glass is used, removal of thecoating that would otherwise extend to underneath the IGU frame(undesirable for long term reliability) is removed prior to integrationinto the IGU. This edge deletion process is meant to be included in themethods above as an alternative embodiment to those listed above.

Integrated Deposition System

As explained above, an integrated deposition system may be employed tofabricate electrochromic devices on, for example, architectural glass.As described above, the electrochromic devices are used to make IGUswhich in turn are used to make electrochromic windows. The term“integrated deposition system” means an apparatus for fabricatingelectrochromic devices on optically transparent and translucentsubstrates. The apparatus has multiple stations, each devoted to aparticular unit operation such as depositing a particular component (orportion of a component) of an electrochromic device, as well ascleaning, etching, and temperature control of such device or portionthereof. The multiple stations are fully integrated such that asubstrate on which an electrochromic device is being fabricated can passfrom one station to the next without being exposed to an externalenvironment. Integrated deposition systems of the invention operate witha controlled ambient environment inside the system where the processstations are located. A fully integrated system allows for bettercontrol of interfacial quality between the layers deposited. Interfacialquality refers to, among other factors, the quality of the adhesionbetween layers and the lack of contaminants in the interfacial region.The term “controlled ambient environment” means a sealed environmentseparate from an external environment such as an open atmosphericenvironment or a clean room. In a controlled ambient environment atleast one of pressure and gas composition is controlled independently ofthe conditions in the external environment. Generally, though notnecessarily, a controlled ambient environment has a pressure belowatmospheric pressure; e.g., at least a partial vacuum. The conditions ina controlled ambient environment may remain constant during a processingoperation or may vary over time. For example, a layer of anelectrochromic device may be deposited under vacuum in a controlledambient environment and at the conclusion of the deposition operation,the environment may be backfilled with purge or reagent gas and thepressure increased to, e.g., atmospheric pressure for processing atanother station, and then a vacuum reestablished for the next operationand so forth.

In one embodiment, the system includes a plurality of depositionstations aligned in series and interconnected and operable to pass asubstrate from one station to the next without exposing the substrate toan external environment. The plurality of deposition stations comprise(i) a first deposition station containing a target for depositing anelectrochromic layer; (ii) a second deposition station containing atarget for depositing an ion conducting layer; and (iii) a thirddeposition station containing a target for depositing a counterelectrode layer. The system also includes a controller containingprogram instructions for passing the substrate through the plurality ofstations in a manner that sequentially deposits on the substrate (i) anelectrochromic layer, (ii) an ion conducting layer, and (iii) a counterelectrode layer to form a stack in which the ion conducting layerseparates the electrochromic layer and the counter electrode layer. Inone embodiment, the plurality of deposition stations are operable topass a substrate from one station to the next without breaking vacuum.In another embodiment, the plurality of deposition stations areconfigured to deposit the electrochromic layer, the ion conductinglayer, and the counter electrode layer on an architectural glasssubstrate. In another embodiment, the integrated deposition systemincludes a substrate holder and transport mechanism operable to hold thearchitectural glass substrate in a vertical orientation while in theplurality of deposition stations. In yet another embodiment, theintegrated deposition system includes one or more load locks for passingthe substrate between an external environment and the integrateddeposition system. In another embodiment, the plurality of depositionstations include at least two stations for depositing a layer selectedfrom the group consisting of the electrochromic layer, the ionconducting layer, and the counter electrode layer.

In some embodiments, the integrated deposition system includes one ormore lithium deposition stations, each including a lithium containingtarget. In one embodiment, the integrated deposition system contains twoor more lithium deposition stations. In one embodiment, the integrateddeposition system has one or more isolation valves for isolatingindividual process stations from each other during operation. In oneembodiment, the one or more lithium deposition stations have isolationvalves. In this document, the term “isolation valves” means devices toisolate depositions or other processes being carried out one stationfrom processes at other stations in the integrated deposition system. Inone example, isolation valves are physical (solid) isolation valveswithin the integrated deposition system that engage while the lithium isdeposited. Actual physical solid valves may engage to totally orpartially isolate (or shield) the lithium deposition from otherprocesses or stations in the integrated deposition system. In anotherembodiment, the isolation valves may be gas knifes or shields, e.g., apartial pressure of argon or other inert gas is passed over areasbetween the lithium deposition station and other stations to block ionflow to the other stations. In another example, isolation valves may bean evacuated regions between the lithium deposition station and otherprocess stations, so that lithium ions or ions from other stationsentering the evacuated region are removed to, e.g., a waste streamrather than contaminating adjoining processes. This is achieved, e.g.,via a flow dynamic in the controlled ambient environment viadifferential pressures in a lithiation station of the integrateddeposition system such that the lithium deposition is sufficientlyisolated from other processes in the integrated deposition system.Again, isolation valves are not limited to lithium deposition stations.

FIG. 8A, depicts in schematic fashion an integrated deposition system800 in accordance with certain embodiments. In this example, system 800includes an entry load lock, 802, for introducing the substrate to thesystem, and an exit load lock, 804, for removal of the substrate fromthe system. The load locks allow substrates to be introduced and removedfrom the system without disturbing the controlled ambient environment ofthe system. Integrated deposition system 800 has a module, 806, with aplurality of deposition stations; an EC layer deposition station, an IClayer deposition station and a CE layer deposition station. In thebroadest sense, integrated deposition systems of the invention need nothave load locks, e.g. module 806 could alone serve as the integrateddeposition system. For example, the substrate may be loaded into module806, the controlled ambient environment established and then thesubstrate processed through various stations within the system.Individual stations within an integrated deposition systems can containheaters, coolers, various sputter targets and means to move them, RFand/or DC power sources and power delivery mechanisms, etching toolse.g. plasma etch, gas sources, vacuum sources, glow discharge sources,process parameter monitors and sensors, robotics, power supplies, andthe like.

FIG. 8B depicts a segment (or simplified version) of integrateddeposition system 800 in a perspective view and with more detailincluding a cutaway view of the interior. In this example, system 800 ismodular, where entry load lock 802 and exit load lock 804 are connectedto deposition module 806. There is an entry port, 810, for loading, forexample, architectural glass substrate 825 (load lock 804 has acorresponding exit port). Substrate 825 is supported by a pallet, 820,which travels along a track, 815. In this example, pallet 820 issupported by track 815 via hanging but pallet 820 could also besupported atop a track located near the bottom of apparatus 800 or atrack, e.g. mid-way between top and bottom of apparatus 800. Pallet 820can translate (as indicated by the double headed arrow) forward and/orbackward through system 800. For example during lithium deposition, thesubstrate may be moved forward and backward in front of a lithiumtarget, 830, making multiple passes in order to achieve a desiredlithiation. Pallet 820 and substrate 825 are in a substantially verticalorientation. A substantially vertical orientation is not limiting, butit may help to prevent defects because particulate matter that may begenerated, e.g., from agglomeration of atoms from sputtering, will tendto succumb to gravity and therefore not deposit on substrate 825. Also,because architectural glass substrates tend to be large, a verticalorientation of the substrate as it traverses the stations of theintegrated deposition system enables coating of thinner glass substratessince there are less concerns over sag that occurs with thicker hotglass.

Target 830, in this case a cylindrical target, is oriented substantiallyparallel to and in front of the substrate surface where deposition is totake place (for convenience, other sputter means are not depicted here).Substrate 825 can translate past target 830 during deposition and/ortarget 830 can move in front of substrate 825. The movement path oftarget 830 is not limited to translation along the path of substrate825. Target 830 may rotate along an axis through its length, translatealong the path of the substrate (forward and/or backward), translatealong a path perpendicular to the path of the substrate, move in acircular path in a plane parallel to substrate 825, etc. Target 830 neednot be cylindrical, it can be planar or any shape necessary fordeposition of the desired layer with the desired properties. Also, theremay be more than one target in each deposition station and/or targetsmay move from station to station depending on the desired process.

Integrated deposition system 800 also has various vacuum pumps, gasinlets, pressure sensors and the like that establish and maintain acontrolled ambient environment within the system. These components arenot shown, but rather would be appreciated by one of ordinary skill inthe art. System 800 is controlled, e.g., via a computer system or othercontroller, represented in FIG. 8B by an LCD and keyboard, 835. One ofordinary skill in the art would appreciate that embodiments of thepresent invention may employ various processes involving data stored inor transferred through one or more computer systems. Embodiments of thepresent invention also relate to the apparatus, such computers andmicrocontrollers, for performing these operations. These apparatus andprocesses may be employed to deposit electrochromic materials of methodsof the invention and apparatus designed to implement them. The controlapparatus of this invention may be specially constructed for therequired purposes, or it may be a general-purpose computer selectivelyactivated or reconfigured by a computer program and/or data structurestored in the computer. The processes presented herein are notinherently related to any particular computer or other apparatus. Inparticular, various general-purpose machines may be used with programswritten in accordance with the teachings herein, or it may be moreconvenient to construct a more specialized apparatus to perform and/orcontrol the required method and processes.

As mentioned, the various stations of an integrated deposition system ofthe invention may be modular, but once connected, form a continuoussystem where a controlled ambient environment is established andmaintained in order to process substrates at the various stations withinthe system. FIG. 8C depicts integrated deposition system 800 a, which islike system 800, but in this example each of the stations is modular,specifically, an EC layer station 806 a, an IC layer station 806 b and aCE layer station 806 c. Modular form is not necessary, but it isconvenient, because depending on the need, an integrated depositionsystem can be assembled according to custom needs and emerging processadvancements. For example, FIG. 8D depicts an integrated depositionsystem, 800 b, with two lithium deposition stations, 807 a and 807 b.System 800 b is, e.g., equipped to carry out methods of the invention asdescribed above, such as the dual lithiation method described inconjunction with FIG. 7C. System 800 b could also be used to carry out asingle lithiation method, e.g. that described in conjunction with FIG.7D, for example by only utilizing lithium station 807 b duringprocessing of the substrate. But with modular format, e.g. if singlelithiation is the desired process, then one of the lithiation stationsis redundant and system 800 c, as depicted in FIG. 8E can be used.System 800 c has only one lithium deposition station, 807.

Systems 800 b and 800 c also have a TCO layer station, 808, fordepositing the TCO layer on the EC stack. Depending on the processdemands, additional stations can be added to the integrated depositionsystem, e.g., stations for cleaning processes, laser scribes, cappinglayers, MTC, etc.

Although the foregoing invention has been described in some detail tofacilitate understanding, the described embodiments are to be consideredillustrative and not limiting. It will be apparent to one of ordinaryskill in the art that certain changes and modifications can be practicedwithin the scope of the appended claims.

What is claimed is:
 1. A method of fabricating an electrochromic device,the method comprising: a. depositing a first portion of a metal oxidelayer; b. lithiating the first portion with elemental lithium; and c.depositing a second portion of the metal oxide layer.
 2. Anelectrochromic device comprising at least one metal oxide layer formedby: a. depositing a first portion of the at least one metal oxide layer;b. lithiating the first portion with elemental lithium; and c.depositing a second portion of the at least one metal oxide layer.